grep
\ngrep is a saviour command for unix users. grep can be used to search for patterns in a file or standard input. The pattern search includes finding the line number of the keyword, counting the number of occurrences of a keyword and many more. we will see in the following examples.<\/p>\n
Example 1) grep in its simplest form,i:e without any arguments displays all the lines where the pattern occurs.<\/p>\n
\/home\/kapoor $ cat AllPhones.lst
\nSamsung C5010 Squash : Rs. 3,245
\n Samsung C5130 : Rs. 3,500
\n LG GU285 : Rs. 3,750
\n Nokia C2 01 : Rs. 3,799
\n Nokia 2730 Classic : Rs. 3,960
\n INQ Mini 3G : Rs. 4,000
\n Spice G6500 : Rs. 4,295
\n Sony Ericsson Cedar : Rs. 5,100
\n Samsung Star Nano 3G S3370 : Rs. 5,100
\n Samsung L700 : Rs. 5,300
\n Spice QT95 : Rs. 5,500
\n nokia 7230 : Rs. 5,700
\n Sony Ericsson J105 Naite : Rs. 5,800
\n Samsung Metro 3G S5350 : Rs. 6,000<\/p>\n
\/home\/kapoor $ grep Nokia AllPhones.lst
\nNokia C2 01 : Rs. 3,799
\n Nokia 2730 Classic : Rs. 3,960 <\/p>\n
To make case insensitive search use grep with \u2013i option
\ni:e grep \u2013i Nokia AllPhones.lst
\nnow the result would also include the line nokia 7230 : Rs. 5,700<\/p>\n
Example 2)
\nIt might be required for you to count the number of occurrences of a particular keyword, use -c option .
\n\/home\/kapoor $ grep -c -i Samsung AllPhones.lst
\n5<\/p>\n
Remember always to use \u2013i just before the search keyword.<\/p>\n
Example 3)
\nYou might be searching a particular thing excluding a particular word, then use -v option.
\n \/home\/kapoor $ grep \u2013v Samsung AllPhones.lst
\nLG GU285 : Rs. 3,750
\n Nokia C2 01 : Rs. 3,799
\n Nokia 2730 Classic : Rs. 3,960
\n INQ Mini 3G : Rs. 4,000
\n Spice G6500 : Rs. 4,295
\nSony Ericsson Cedar : Rs. 5,100
\nSpice QT95 : Rs. 5,500
\n nokia 7230 : Rs. 5,700
\n Sony Ericsson J105 Naite : Rs. 5,800 <\/p>\n
Example 4)
\nWhen you wish to search more than one keyword use \u2013e option of grep before each keyword.<\/p>\n
\/home\/kapoor $ grep -e LG \u2013e \u2013i spice AllPhones.lst
\nLG GU285 : Rs. 3,750
\nSpice G6500 : Rs. 4,295
\nSpice QT95 : Rs. 5,500 <\/p>\n
Similarly if you require to search for all other phones other than LG and spice use
\ngrep -v -e LG \u2013e \u2013i spice AllPhones.lst<\/p>\n
Example 5)
\nTo accomplish a search within a searched line use pipes. suppose you are planning to buy
\n a nokia phone other than a classic one, use grep as shown
\n\/home\/kapoor $ grep \u2013i nokia AllPhones.lst | grep -v \u2013i Classic
\nNokia C2 01 : Rs. 3,799
\nnokia 7230 : Rs. 5,700<\/p>\n
why grep is such a great command in searching these results for you is that it does them amazingly fast.<\/p>\n
Example 6) Save the list of phones in a file. Similarly you can use \u2013v \u2013f The situation is like this. You have a key word and you want to search it in a large number of Example 7) Example 8) If you do not want grep to display the searched filenames and only want the patterns use grep -h Example 9) \/home\/kapoor $grep -l -r awk *.sh Example 10) Example 11) \/home\/kapoor $ grep \u2013n error status-run.log alias<\/p>\n alias<\/p>\n alias is one of those commands for people who want to be lazy. you can use alias Example. 1) To make this happen every time you work after logging in, save the above line in after saving it in .profile do not forget to run it. Example2) after running .profile ,to view all the aliases that are set globally, just enter alias.<\/p>\n \/home\/viru$ alias seems viru is so lazy..!!<\/p>\n Example3) There is another way to accomplish this,that is by using quotes (\u2018\u2019) after a command.the following lines show how. Aliases which are defined outside a script or in your .profile do not work inside scripts. so make sure not to use aliased words in a shell script to contain their actual values used outside.<\/p>\n df<\/p>\n df Reducing the space occupied by a file system helps to boost system performance by making Example 1) Consider the output of df \u2013gt.<\/p>\n \/home\/Prod$ df \u2013gt. The output of the command might not look organised in some unix systems.ie: alignment does not seems to be right, \/home\/Prod$ df \u2013gt | awk ‘BEGIN{aa=”Filesystem”;bb=”GB blocks”;cc=”Used”;dd=”Free”;ee=”Used”;ff=”Mounted on”;printf(“%-40s %9s %6s %6s %6s %-11s\\n”,aa,bb,cc,dd,ee,ff);} {if($1!=”Filesystem”){printf(“%-40s %9s %6s %6s %6s %-9s\\n”,$1,$2,$3,$4,$5,$6) } }’<\/p>\n Filesystem GB blocks Used Free Used Mounted on Now ,that seems to be a much better organised output. Use this in a script and keep an Example 2) Example 3) Every file has an inode value of 1 and a directory has an inode value of 2.<\/p>\n To see the Inode values along with other attributes,use df \u2013i, and off course with awk filtering.(Use different values before %s for proper alignment)<\/p>\n \/home\/Prod$ df -i wc<\/p>\n wc Example 1) \/home\/mark$ wc Bulk-SMS-file.txt The individual values can be retrieved as field through awk , but wc provides options.<\/p>\n wc -l : Total Lines<\/p>\n wc -w : Total words<\/p>\n wc -c : Total bytes<\/p>\n wc -k : Total characters<\/p>\n The wc command considers a word to be a string of characters of non-zero length which are delimited by a white space and lines are counted when newline characters occur.<\/p>\n Example 2) \/home\/mark$ ls file_list-201111* \/home\/mark$ wc -l file_list-201111* This gives you the no of lines in every file as well as the sum of all the individual line counts.<\/p>\n Same command can be run without the -l option to get the counts of various parameters and their totals.<\/p>\n Example 3) \/home\/mark$ echo “I Love You” | wc Hmm! wc achieved something cool this time\u2026<\/p>\n Similarly you can use wc -l as an alternative to grep -c. Is same as<\/p>\n \/home\/mark$ grep tremendous Director-speech.txt | wc -l <\/p>\n Example 4) Assume that you have a continuous file, i.e. a file which has same number of characters (or bytes ) in each line. \/home\/mark$ wc -l All_Customers.lst The following steps explain the method.<\/p>\n Step1) Step2) \/home\/mark$ fsize=` ls -lrt All_Customers_1000.lst | awk \u2018{ print $5}\u2019` Now ,fratio actually stores the number of bytes per file.<\/p>\n Step3) Which is same as calculated by wc -l. If there are multiple files of such types (such as file_list-201111*) and all have the same fratio.(defined above),then you can write a script to get the similar output as that of The script is as shown. Here ,between the output of ls giving sizes of all the files ,a \u2018 +\u2019 symbol is placed and 0 at the end and is passed to bc command as an expression whose value (the sum) is divided by the tail<\/p>\n tail<\/p>\n tail command is one of my favourite commands because of its usefulness in viewing the last few lines of a required file and also what is being written into a file ( using \u2013f option).it can also be used to see the progress of cp, mv, tar and other commands.<\/p>\n tail by default shows last ten lines of a file.it can be made to view any last \u2018n\u2019 lines where n is a number<\/p>\n Example 1) Example 3) \/home\/k109$cat worldsport.txt If it is required to view the file starting from second line,use<\/p>\n \/home\/k109$tail +2 worldsport.txt sort<\/p>\n sort Example1) \/home\/jones$ cat flowers.txt If you want to sort it in reverse order ,use Example2) To default sort(without any option) would give Here it sorted the letters starting with uppercase first and then sorted lower case ones, Now use sort -f Example3) \/home\/jones $ grep error cron.log | sort -u Example 4) Now, The output of default sort command is shark|fish|6 Here -t \u201c|\u201d tells the sort command do sorting on fields delimited by a \u201c|\u201d character. If you do not use -t option, sequence of space characters is considered as default delimiter . \u201c+1\u201d instructs sort to ignore the first field or sort from second field.<\/p>\n Similarly if you wanted to sort it based on the third column, just using +2 instead of +1 might not work in the given example. The output of that sort command would be as follows.<\/p>\n \/home\/jones$ sort -t \u201c|\u201d +2 detailed-list.csv \/home\/jones$ sort -n -t \u201c|\u201d +2 detailed-list.csv Example5) Suppose you wanted to sort this list such that sorting should start from 3rd column of 1st field and 4th column of 1st field. Here fields are separated by one or more spaces. Columns here refer to characters.<\/p>\n \/home\/jones$ sort -k1.3,1.4 num-luck To sort from 2nd column of 1st field and 3rd column of second field in reverse order,<\/p>\n \/home\/jones$ sort -k1.2,2.3r num-luck Similarly, to sort lines based on 1st and 3rd fields, use Example 6) \/home\/jones$ sort -o flowers.txt flowers.txt <\/p>\n The syntax is sort \u2013o Example 7) The sort command sort -t \u201c|\u201d +1 detailed-list.csv in example 4 can be written as sed<\/p>\n sed Example2) \u00b7 To print all the lines of a file between the first occurrences of two patterns This prints all the lines starting from the line which has the first occurrence of \u2018 industry\u2019 and the first occurrence of \u2018station\u2019 .<\/p>\n \u00b7 To print all the lines of a file starting from its first line and the line of first occurrence of \u2018industry\u2019, \u00b7 To put all the lines starting from line with the first occurrence of the pattern \u2018industry\u2019 in the file to the last line of the file into standard output(i.e. print).<\/p>\n sed \u2013n \u2018\/industry\/,$p\u2019 general-dates.prt<\/p>\n \u00b7 To print all the lines starting from the line containing the pattern string whose value is stored in a variable $ptrn to the 15th line of the file.<\/p>\n sed \u2013n \u2018\/\u2019$ptrn\u2018\/,15p\u2019 general-dates.prt<\/p>\n The pattern space can contain more complex regular expressions .<\/p>\n Example3) \u00b7 To add a \u201c,\u201d character between the original pattern and replacement string defined by ${string_pattern}\u2019 and ${replace_string} respectively . Example 4) Now if I want to change the directory structure on line number 4 from \/home to \/var, sed can be used as follows.<\/p>\n \/home\/UAT$ sed \u20184 s\/home\/var\/\u2019 dir_struct Here we substituted only home with var in the 4th line .If you need to substitute \/home\/vd2 with \/var\/vd1 , you would have written the command as follows. sed \u20184 s#\/home\/vd2#\/var\/vd1#\u2019 dir_struct<\/p>\n Example 5) The command above replaced only the 2nd occurrence of a digit followed by \u201cth\u201d. \/home\/jade$ echo “1st 2nd 3rd 4th 5th 6th”|sed “s\/[0-9]th\/\/2g” rsh<\/p>\n rsh<\/p>\n rsh is used to execute commands on a remote machine. Prerequisites 1) make a list of the users of both the local and remote hosts and their $LOGNAME s who are going to use rsh to run commands or scripts.<\/p>\n 2)Open the required ports which is going to be used for rsh and rcp.<\/p>\n 3)make an entry of remote host in \/etc\/hosts file of the local host and an entry of local host in \/etc\/hosts of the remote host. This change can done my root user,if you do not have root access then contact your unix admin.<\/p>\n A sample entry is as shown, assume that your hostname is mahaprana and the IP address is 158.0.125.23, Then the remote host\u2019s \/etc\/hosts file must contain a line the comments (3rd column) is optional. 4)The list of users are to be placed in $HOME\/.rhosts file of both local and remote hosts for every user. \/home\/ajay$echo $HOME And entries shown below in the remote host.<\/p>\n \/home\/ajay$hostname \/home\/bhaskar\/ cat $HOME\/.rhosts After these changes are made, you can run the rsh command as shown in following examples.<\/p>\n Example 1) This runs the command \u2018ls inter* \u2018 in the remote host 158.0.125.45 as user ajay. Example 2) \/home\/ divya$ rsh 158.0.125.45 -l bhaskar \u201c grep -i beatles Albumlist\/old\/Film \u201d To run multiple commands in the remote host use semicolon to separate them. \/home\/ ajay$ rsh 158.0.125.45 -l bhaskar \u201c echo $ORACLE_HOME; sqlplus \/\u201d rm<\/p>\n rm<\/p>\n rm is used to remove files or directories. It can be used interactively to ask user input while removing multiple files or the contents of a directory.<\/p>\n A great care has to be taken before running rm command. There is no way to recover the files which are removed unless they were backed up on tape.<\/p>\n Use rm Example 1) \/home\/jenny$ls city_DETAIL*.lst If the file does not belong to the current user, or if the file does not have write permissions, the rm: remove City_DETAIL_KOL.lst??.lst<\/p>\n If you do not want to answer to this question to all the files, use \u2013f option to remove forcefully.<\/p>\n rm -f City_DETAIL_???.lst<\/p>\n Example 2) remember that you cannot remove a directory if it is the path of your working directory or a parent when you are inside its subdirectories. \/home\/jenny \/FILMS$ rm -rf \/home\/jenny \/FILMS #Does not work To view the files which are being removed when files are removed in bulk.<\/p>\n Suppose you have a file containing the list of files to be removed. then home\/jenny$sed \u2018s\/^\/rm -ef \/g\u2019 file_to_remove_list > file_to_remove_list.sh Example 4) y and n are inputs given by you to remove or not to remove resp.<\/p>\n rcp<\/p>\n rcp Assume your hostname is Prod-serv and IP is 192.158.0.140 and the remote hostname is Example 1) \/home\/kumar$ rcp Audit_document.txt warren@192.158.0.120:<\/p>\n This sends the local file Audit_document.txt to the host Test-serv (you can use Test-serv in place of the IP address) and places it in the $HOME directory of warren. Example 2) rcp just like cp changes the modification time(time stamp) of the destination file to the latest time. To retain the same time stamp use rcp \u2013p . The above example can be written as<\/p>\n rcp -p warren@192.158.0.120:global\/Meal_pass2.prt .<\/p>\n Example 3) \/home\/kumar$ ls -ld localdir \/home\/kumar$rcp -r localdir warren@192.15.0.120: More examples: To copy the file \u2018pattern-styles.tar.gz\u2019 to \/home\/warren\/images directory of 192.15.0.120 as style1.tar.gz with same time stamp. ps<\/p>\n ps Example 2) Example 3) All your processes and the processes of other users can be viewed.<\/p>\n In the output of the command above ,the various column heads are defined as follows. UID PPID C STIME TTY CMD paste<\/p>\n paste Example 1) \/users\/higgs$ cat End_Times.log If you have to combine these files such that the start and end times of a function appear on a common line, use paste as follows.<\/p>\n \/users\/higgs$paste Start_Times.log End_Times.log Notice that one space was added in between the two same rows of the two files .This In some cases you may need to place a different delimiter between lines of the row.<\/p>\n \/users\/higgs$ paste -d \u2018,\u2019 Start_Times.log End_Times.log >Start_end_times.csv. Open this file Start_end_times.csv in windows excel if you want a better view.<\/p>\n Example 2) Imagine you have two files \/users\/higgs$cat Showtime.log \/users\/higgs$paste -s Booked.log Showtime.log<\/p>\n Don2 Sherlock_homes Mission_Impossible4 The_Dirty_picture mv<\/p>\n mv Example 1) This renames the file from yog_LIST to jeev_LIST Example 2) Here oracle_logs is a directory.if you want to save the log with a different name,enter Example 3) \/home\/yogi$ ls \u2013lrt CONSIGNMNENT* CONSIGNMNENT-OLD: \/home\/yogi$ mv CONSIGNMNENT* \/ALL_CONS\/DOCS<\/p>\n This moves all the entities listed above to \/ALL_CONS\/DOCS directory if it exists, otherwise the command gives an error Remember that when there are more than 2 arguments to mv , the last argument is considered the destination directory. When there are only 2 arguments, if the 2nd argument contains a \u2018\u2019\/\u201d in it, then the directory structure must exist.<\/p>\n Example 3) more<\/p>\n more<\/p>\n sometimes, while viewing huge files it would be necessary to view it such that the Example 1) Then to open it and view it page wise enter Example 2) Example 3) \/home\/g321$more -15 greenlife.txt<\/p>\n mkdir<\/p>\n mkdir Example1)To simply create a directory or a directory structure. \/home\/MUM-user$mkdir -p channels\/ STAR\/NGC\/Speed These commands will create all the intermediate parent directories and the final directory.<\/p>\n Example 2) \/home\/MUM-user\/ $ mkdir -p -m 775 channels\/discovery man<\/p>\n man Example 2: ls<\/p>\n ls Example 1) Example 2) Example 3) \/home\/script-user $ ls \u2013lrt The first field here shows file permissions, which are discussed in chmod, You can get any field of the output of ls \u2013lrt using awk. The \u2018^\u2019 character represents a starting character of a line( a \u2018$\u2019 represents end), in fact it\u2019s not physically seen, but an interpreted character. Example 5) Suppose you want to view all the files of the directory java use ls \u2013lrt java instead of doing both cd java and ls \u2013lrt.<\/p>\n Example 6) home\/script-user\/docs$ls | grep \u2013i report The above command is equivalent to ls *report* *Report* *REPORT* *Report*\u2026\u2026\u2026..and so on till all the combination of the word report in Ucase and Lcase.<\/p>\n Example 7) java:<---------------------------- directory\n java The J2EE Tutorial (Addison Wesley & Sun, 2002).pdf\n(Addison Wesley 2002) - Java Network Programming and Distributed Computing.pdf\n(Ebook) Java - Borland Jbuilder - Developing Database Applications - Inprise.pdf\n(OReilly) Java Network Programming ,2nd Ed.pdf\n(OReilly) Java Server Pages ,2nd Ed.pdf\n\njava scripts:\n\n[Java Script] O'Reilly- JavaScript The Definitive Guide.pdf\n\njava scripts\/newdir:<------------- subdirectory\n[Java Script] O'Reilly - JavaScript The Definitive Guide 2ed.pdf\n\u2026.\n\u2026.\n\u2026\n^C\n\nExample 8)\nls by default does not show hidden files and directories. To show hidden files use \u2013a option.\nEg: files like .profile, .sh_history etc are hidden files. if have not used \u2013a option you wont be\n able to see these files.\nIn all the directories , there are 2 common hidden directories .(a dot) which represents the current directory and ..( 2 dots) represents the parent of the current directory\n\n\nkill\n\nkill \nkill is used to send a signal to the process, though the name suggests that it is used only to terminate a process. But, kill helps to terminate a process more often than not. When some process is run unexpectedly or accidentally, it might have to be aborted ,for which kill helps just like CTRL+ALT+DEL in windows .\n\nExample 1)\nps command gives you the process id s and other details of various commands, if you want to stop any command, just check the corresponding PID of the process(the command) which you want to terminate ,then use kill to stop that process.\n\nConsider the output of ps,\n\n\/home\/b6789$ps -fu b6789\nUID PID PPID C STIME TTY TIME CMD\nb6789 352266 1 0 05:32:38 - 0:14 java \/usr\/bin\/wc \u2013l \nb6789 368734 1 0 05:32:42 - 0:07 [wc]\n------b6789 372912 120 0 05:32:43 - 5:10 java \/usr\/bin\/java\/dev2.java \nb6789 409806 1 0 05:32:39 - 0:13 java \/usr\/bin\/java\/start-atm.java\n\n this process is consuming cpu and has to be terminated,\n\n\/home\/b6789$kill 372912\nThis sends the signal SIGTERM to the process 372912, and terminates it.\nSometimes the process may refuse to terminate just by SIGTERM, in that case use SIGKILL signal(kill -9)\n\/home\/b6789$kill -9 372912\n\nThis signal cannot be ignored . You can kill any of the process initiated by you, i:e from your user id this way .A root user has the privilege of killing any user\u2019s processes .\n\nExample 2)\nYou can also get the specific PID for your command without having to search it using grep and awk along with ps. Then kill the PID which you have retrieved.\n\nIf you had to kill the CMD start-atm.java above,\n\/home\/b6789$j_pid=`ps \u2013fu $LOGNAME | grep start-atm.java | grep \u2013v grep | awk \u2019{print $2}\u2019`\n\/home\/b6789$echo $ j_pid\n409806\n\/home\/b6789$kill -9 $ j_pid\n\nYou can also use xargs to kill process of a particular type all at once .\n\nExample 3)\nThere is a method to kill all the processes initiated by you, \n\n\/home\/b6789$kill -9 -1\n\nThis will kill all the processes of your user id and also closes your login session. It is a very dangerous command ,so think thrice and check whether any required process is still running using ps before you press enter.\n\n\n\n\nYou can send many kinds of signals to a process(not all) by using kill - Name num Description SIGKAP 60 keep alive poll from native keyboard Example 4) Now in between if you want to suspend it. take an other session for the same user and run where To restart the command,simply run Similarly other commands ,jobs or utilities can be stopped and continued using kill -17 and kill -19 resp.<\/p>\n Example 5) head<\/p>\n head Example 1) If you wish to view only first two lines of the file, use Example 2) \/home\/ftpusr$ head -1000 migratory_note > migratory_note_1000 Example 3) \/home\/ftpusr$ Suppose you want the first occurring prime number containing 7, Example 4) \/home\/ftpusr$ head -100 operating-out.sh | tail -1 gzip and tar<\/p>\n gzip and tar First we will discuss with examples the individual command usages of gzip and tar and later use them in combination. Example 1) To compress a file stake-holder.csv , \/home\/gr-adm$ gzip file stake-holder.csv Example 2) To compress the file stake-holder.csv and save the .gz file in some other directory,<\/p>\n \/home\/gr-adm$ gzip -c stake-holder.csv >\/backup\/stakes\/ stake-holder.csv.gz.<\/p>\n You can also append the compressed file into an existing .gz file. Here , Old-stake-holder.csv.gz can be a pre existing .gz file or a new file with that name will be created.<\/p>\n Example 3) Example 4) gzip \u2013dc stake-holder.csv.gz | head -5 >stake-holder-five.csv.<\/p>\n tar.<\/p>\n tar is a short form for tape archive. It can create a single file with the contents of a directory structure in one path or extract a file into directory structure in another path.<\/p>\n Example1) \/home\/gr-adm$ tar -cvf \/archives\/archive2\/data-history.tar data\/notes This creates an archive file data-history.tar in the path \/archives\/archive2 which contains the directory \/home\/notes and all its files and directory structure.<\/p>\n Example2) \/home\/gr-adm$ cd \/base-app\/archive Example3) Now to create an archive of only these specific files ,use tar in the following manner.<\/p>\n \/home\/gr-adm$ tar -cvf \/archives\/archive2\/data-specific.tar -L to-tar-list Example4) \/home\/gr-adm$ cat \/home\/fiuser\/excl-list \/home\/gr-adm$ tar -X \/home\/fiuser\/excl-list -cvf \/archives\/data-specific2 .tar data\/notes Example5) \/home\/gr-adm$ tar -tvf \/archives\/data-specific2 .tar Now that we have gone through tar and gzip individually in detail, let us discuss with examples the use of combined forces of tar and cd command.<\/p>\n \u00b7 to take the tar of data\/notes directory and untar the contents in \/archives\/archive2<\/p>\n tar cvf \u2013 data\/notes | (cd \/archives\/archive2;tar xvf – )<\/p>\n \u2018 \u2013\u2018 refers to the console .so it means you are passing the output of tar -cvf to tar \u2013xvf and changing your path to \/archives\/archive2.<\/p>\n \u00b7 to take the tar of local directory data\/notes and untar the contents in a directory \/archives\/archive2 of remote machine 10.198.150.45<\/p>\n tar cvf – data\/notes | rsh 10.198.150.45 -l remuser “cd \/archives\/archive2;tar xvf -;”<\/p>\n \u00b7 to take the tar of files in list file tar_list_1 and untar in \/archives\/archive2<\/p>\n tar cvf – `cat tar_list_1` | (cd \/archives\/archive2;tar xvf – )<\/p>\n \u00b7 to take the tar of files in a local list file tar_list_1 and untar in \/archives\/archive2 of a remote machine 10.198.150.45<\/p>\n tar cvf – `cat tar_list_1` | rsh 10.198.150.45 – l remuser “cd \/archives\/archive2;tar xvf -”<\/p>\n \u00b7 to take the tar of data\/notes directory excluding those in excl_list_tar and untar its contents in \/archives\/archive2<\/p>\n tar \u2013X excl_list_tar cvf – data\/notes | (cd \/archives\/archive2;tar xvf -)<\/p>\n Finally we will discuss with examples the combined use of gzip and tar.<\/p>\n \u00b7 to gunzip a zipped tar file data_archive.tar.gz and untar It in \/archives\/archive2 .<\/p>\n gzip -dc data_archive.tar.gz – | (cd \/archives\/archive2;tar xvf -)<\/p>\n \u00b7 to gunzip a local zipped tar file data_archive.tar.gz and untar it in \/archives\/archive2 of a remote machine 10.198.150.45 \u00b7 To view the contents of a zipped tar file without unzipping it, page wise<\/p>\n gzip -dc data_archive.tar.gz – | tar tvf – |pg<\/p>\n find<\/p>\n find Example 1) Suppose that you want to know the entire directory structure in a This command searched all the directories starting from \/home\/Varsha and displayed it. To display everything(i:e all Example 2) The output you get are the values included in the following order Example 3) Then use this file list(file_list_5) to take a tar of the file, or to remove those files and save this file as a copy of \u2018which files have been archived\u2019. Example 4) Suppose you want the list of files which are of size greater than 100kB,use find as follows. Example 5) \/home\/varsha\/$ touch -t 201305310625 test_file<\/p>\n home\/varsha\/$ ls -lrt test_file home\/varsha\/$ find . -newer test_file You can verify it by using -ls option.<\/p>\n echo<\/p>\n echo<\/p>\n echo is used to display characters into standard output. It can also be used to write to a file Example1) \/home\/b4578$ echo \u201c my Home is $HOME\u201d To print the $symbol use a backslash \u201c\\\u201d character. Example 2)
\nYou have seen in Example 4) how multiple keyword search was done using \u2013e option. but it becomes very lengthy and untidy to use \u2013e after each keyword if there are 100s of things to be searched.
\nIn such cases you can use grep with -f
\n\/home\/kapoor $cat >required_phones
\nSony Ericsson
\nINQ
\nNokia
\n^D
\n\/home\/kapoor $grep \u2013f required_phones AllPhones.lst
\n Nokia C2 01 : Rs. 3,799
\n Nokia 2730 Classic : Rs. 3,960
\n INQ Mini 3G : Rs. 4,000
\n Sony Ericsson Cedar : Rs. 5,100
\nSony Ericsson J105 Naite : Rs. 5,800 <\/p>\n
\nfiles in a path. The following examples (7-9)show you various techniques and scenarios.<\/p>\n
\nTo give only a list of files which contain your keyword use \u2013l option of grep.
\nThe command below lists all the scripts which uses awk .
\n\/home\/kapoor $grep -l \u201cawk\u201d *.sh
\nPattern-gen.sh
\nLarge-box.sh<\/p>\n
\nIf grep is used to search in a group of files for a pattern, it gives the following default output.
\n \/home\/kapoor $grep sed *.sh
\n pgfile-2.sh:sed -n 1,$p $h2_file.txt
\n pgfile-2.sh:sed ‘s\/;\/\/g’ $h3_file.txt
\n daily-b1.sh:sed ‘s\/-\/_\/g’ prime_f.js<\/p>\n
\ngrep -h sed *.sh gives you the output.
\n sed -n 1,$p $h2_file.txt
\n sed ‘s\/;\/\/g’ $h3_file.txt
\n sed ‘s\/-\/_\/g’ prime_f.js<\/p>\n
\nTo search for patterns recursively among files of directory and its sub directories use grep -r .<\/p>\n
\nPattern-gen.sh
\nLarge-box.sh
\nShell1\/getfiles_2.sh
\nShell1\/remainder.sh
\nShell1\/byte-logs.sh
\nShell1\/new-scripts\/byte-logs.sh
\nShell2\/vault-value.sh<\/p>\n
\nIn shell scripts you may need to search for a pattern but do not want the command to write to
\nStandard output but you need to decide on whether the search succeeded, then use grep \u2013q.
\n….. #lines of the script
\n….. \u2018\u2019
\ngrep -q win victory-status.log
\nif [ $? -eq 0 ]
\nthen
\n flag=1
\nelse
\nflag=0
\nfi
\n..
\n..
\nHere grep does not give any output, but the exit condition is 0 if search is found and non zero if not found ( $? Stores the exit condition of the output of previous command.)<\/p>\n
\nYou can also know the line numbers of the searched patterns through grep by using \u2013n command.<\/p>\n
\n40: error cannot open file gt1.txt
\n160:error cannot open file uu6.txt
\n178:parse error<\/p>\n
\nin situations where it is too time consuming to type the same commands again and again.
\nBut avoid aliases to commands like rm, kill etc.<\/p>\n
\nTo always use vim instead of vi, and to make sure that whenever
\n there is a system crash, network failure etc during editing ,
\nall the contents are recovered, use the alias as follows.
\n\/home\/viru$ alias vi = \u2018vim \u2013r\u2019<\/p>\n
\nyour .profile
\ni:e in the file $HOME\/.profile<\/p>\n
\nie \/home\/viru$ . $HOME\/.profile
\n |
\n |
\n a dot here is necessary.<\/p>\n
\nalias ls=\u2019ls \u2013lrt\u2019
\nalias psu=\u2019ps \u2013fu $LOGNAME\u2019
\nalias df =\u2018df \u2013gt\u2019
\nalias jbin=\u2019cd \/home\/viru\/utils\/java\/bin\u2019
\nalias jlib=\u2019cd \/home\/viru\/utils\/java\/lib\u2019<\/p>\n
\nTo prevent the effect of aliases defined for a word, token or a command, use unalias.
\n\/home\/viru$ unalias jbin
\n\/home\/viru$ jbin
\nJbin:not found<\/p>\n
\n\/home\/viru$ alias same
\nalias same=\u2019\/opt\/bin\/samefile.exe\u2019
\n\/home\/viru$ same \u2018\u2019
\nsame:not found.
\nThe effect of alias was nullified for the word same. If you use double quotes after an aliased command name ,(eg: alias df =\u2018df \u2013gt\u2019) then the actual command will be run.(ie df\u2019\u2019 would run \/usr\/bin\/df instead of df -gt)<\/p>\n
\ndf command gives you the information of the disk spaces. It is a very good command for
\nsystem administration and file system monitoring. You can also view various parameters
\nlike total number of files in a particular file system and maximum allocated values.<\/p>\n
\nThe applications and utilities that use these file systems take lesser time for accessing data,
\nSo constantly running df helps.<\/p>\n
\ndf comes various options like -g,-m,-k etc which helps you to view file system sizes in gigabytes, megabytes or kilobytes blocks resp , including t gives total allocated space.<\/p>\n
\nFilesystem GB blocks Used Free Used Mounted on
\n\/dev\/hd4 0.75 0.35 0.40 48% \/
\n\/dev\/hd2 5.50 3.68 1.82 67% \/usr
\n\/dev\/hd9var 4.00 0.63 3.37 16% \/var
\n\/dev\/hd3 4.62 0.71 3.91 16% \/tmp
\n\/dev\/hd1 8.25 3.96 4.29 48% \/home
\n\/dev\/hd10opt 4.50 1.30 3.20 29% \/opt
\n\/dev\/lv00 0.12 0.00 0.12 4% \/var\/adm\/csd
\n\/dev\/fslv00 5.00 0.03 4.97 1% \/utilities
\n\/dev\/ora10g_lv 15.00 5.18 9.82 35% \/ora10g<\/p>\n
\nUse awk for help.<\/p>\n
\n\/dev\/hd4 0.75 0.35 0.40 48% \/
\n\/dev\/hd2 5.50 3.68 1.82 67% \/usr
\n\/dev\/hd9var 4.00 0.63 3.37 16% \/var
\n\/dev\/hd3 4.62 0.71 3.91 16% \/tmp
\n\/dev\/hd10opt 4.50 1.30 3.20 29% \/opt
\n\/dev\/lv00 0.12 0.00 0.12 4% \/var\/adm\/csd
\n\/dev\/fslv00 5.00 0.03 4.97 1 % \/utilitie\/dev\/hd1
\n\/dev\/hd1 8.25 3.96 4.29 48% \/home
\n\/dev\/ora10g_lv 15.00 5.18 9.82 35% \/ora10g<\/p>\n
\nalias for df command to this script named df.<\/p>\n
\nTo constantly monitor disk space you can make a script and run it constantly.
\n\/home\/Prod$ cat disk-monitor.sh
\n#!\/usr\/bin\/ksh
\nfor Pspace in `df -gt | awk \u2018{ print $4}\u2019 | grep \u2013v -e used -e \/ora | tr -d \u2018%\u2019 `
\ndo
\nif [ $ Pspace -gt 80 ]
\nthen
\nalarmfunc #call the alarm function.
\nfi
\ndone<\/p>\n
\n df is also helpful in knowing number of files present in a mount point.
\nIt is also referred to as Inode. For all all the file system mount points there is a
\nInode value assigned which gives the maximum number of files that can be placed in the file system. When the number of files exceed too a large value, you get \u2018parameter list is too long\u2019
\nerror with commands that use wildcards as arguments to filename.<\/p>\n
\nFilesystem 512-blocks Free %Used Iused %Iused Mounted on
\n\/dev\/hd0 19368 9976 48% 4714 5% \/
\n\/dev\/hd1 24212 4808 80% 5031 19% \/usr
\n\/dev\/hd2 9744 9352 4% 1900 4% \/site
\n\/dev\/hd3 3868 3856 0% 986 0% \/tmp
\n \/dev\/hd1 56890 23409 41% 2345 40% \/home <\/p>\n
\nwc is a very useful utility which can count lines, characters, words, bytes etc in a plain text file
\nor standard input. In shell scripts, It helps to store a value for the total lines of a file or output of
\na command into a variable for subsequent use. The examples below show how these things can be achieved.<\/p>\n
\nTo get the counts of lines, words and bytes of a file use wc as follows.<\/p>\n
\n 45 140 990——————————> No of bytes
\n | |———-> No of Words
\nNo of lines <\/p>\n
\nUsing wc on multiple files.<\/p>\n
\nfile_list-20111105.txt
\nfile_list-20111113.txt
\nfile_list-20111120.txt
\nfile_list-20111128.txt<\/p>\n
\n 98164 file_list-20111105.txt
\n 531665 file_list-20111113.txt
\n 527303 file_list-20111120.txt
\n 564207 file_list-20111128.txt
\n 1721339 total<\/p>\n
\nwc can also count these values from standard output through pipes.<\/p>\n
\n 1 3 17<\/p>\n
\n\/home\/mark$ grep \u2013c tremendous Director-speech.txt <\/p>\n
\nwc -l may consume a lot of time on counting the line numbers when the size of the file is huge.
\nIf we are sure that every line in a file contains equal number of characters, there is a faster method to achieve it.<\/p>\n
\n\/home\/mark$ ls -lrt All_Customers.lst
\n-rw-r–r– 1 mark Administ 1321655460912 Dec 16 14:37 All_Customers.lst<\/p>\n
\n23456898<\/p>\n
\nsave the first thousand lines of the file in a separate file.
\n\/home\/mark$ head -1000 All_Customers.lst > All_Customers_1000.lst`<\/p>\n
\nget the ratio of the total size of the file to the line count(1000) of the file.
\n\/home\/mark$ ls -lrt All_Customers_1000.lst
\n-rw-r–r– 1 mark Administ 56344000 Dec 16 14:37 All_Customers.lst<\/p>\n
\n\/home\/mark$ fratio=`expr $fsize \/ 1000`
\n\/home\/mark$ echo $fratio
\n56344<\/p>\n
\nNow divide the total size of All_Customers.lst with fratio.
\n\/home\/mark$tot_lines=` expr 1321655460912 \/ $fsize`
\n\/home\/mark$echo $tot_lines
\n23456898<\/p>\n
\nAll These steps can be used in a shell script for any given file of this type.<\/p>\n
\n wc \u2013l file_list-201111*<\/p>\n
\nfratio=313
\ntot_val=0
\nfor stream in `ls file_list-201111*`
\ndo
\nstr=`ls -lrt $stream|awk ‘{print $5 ” + “}’|tr -d “\\n”|sed ‘s\/$\/0\/’`
\nval=`echo “($str)\/$fratio”|bc`
\necho \u201c$val $stream ”
\ntot_val=`expr $tot_val + $val`
\ndone
\necho ” $tot_val total ” <\/p>\n
\nratio just as explained in the 3 steps above.<\/p>\n
\nto view the last 1000 lines of a huge script page wise ,
\n\/home\/k109$ tail -1000 valuefind.sh | pg
\n……………..
\n……………… #lines of scripts
\n………..
\n.
\n.
\n.
\n……………..
\nStandard input <--- #here pg waits and asks for you to enter a key before which it displays the next page. This is helpful in analysing a script or debugging it page wise.\n\n\nExample 2)\nTo view the file contents while it is being written, use \u2013f option. If an application is writing continuously into a file and to know what is being written, this option can be used.\nOne disadvantage of this command is however that it cannot be used inside scripts because once\nThe application stops writing to a file the command does not come out of tail directly and requires some signal like stop or kill to come out.\n\n Suppose a file is being written by cp command, you can use tail \u2013f
\nexactly what is being written.<\/p>\n
\nTo view the contents of the file starting from a particular line, use tail +
\nSuppose you have a file worldsport.txt<\/p>\n
\nThe game is played on a rectangular field of grass or green artificial turf, with a goal in the middle of each of the short ends. The object of the game is to score by driving the ball into the opposing goal. In general play, the goalkeepers are the only players allowed to touch the ball with their hands or arms, while the field players typically use their feet to kick the ball into position, occasionally using their torso or head to intercept a ball in midair. The team that scores the most goals by the end of the match wins. If the score is tied at the end of the game, either adraw is declared or the game goes into extra time and\/or a penalty shootout, depending on the format of the competition.<\/p>\n
\nshort ends. The object of the game is to score by driving the ball into the opposing goal. In general play, the goalkeepers are the only players allowed to touch the ball with their hands or arms, while the field players typically use their feet to kick the ball into position, occasionally using their torso or head to intercept a ball in midair. The team that scores the most goals by the end of the match wins. If the score is tied at the end of the game, either adraw is declared or the game goes into extra time and\/or a penalty shootout, depending on the format of the competition.<\/p>\n
\nSort , as the name suggests sorts a file or output of a command. Various options determine the sort criteria which are called as sort keys. If multiple files are passed as parameters to sort the output of sort is concatenated.
\nSorting is done in ascending lexicographic order , I e the way in which it appears in a dictionary. If a file contains numbers and alphabet both, by default sort places the sorted alphabets first and then the numbers.<\/p>\n
\nConsider a file containing values as shown.<\/p>\n
\nrose
\nlily
\ntulip
\nmarigold
\nhibiscus
\nChrysanthemum
\n\/home\/jones$ sort flowers.txt
\nChrysanthemum
\nhibiscus
\nlily
\nmarigold
\nrose
\ntulip<\/p>\n
\n\/home\/jones$ sort -r flowers.txt
\ntulip
\nrose
\nmarigold
\nlily
\nhibiscus
\nChrysanthemum<\/p>\n
\nIf you want the sort to to be case insensitive sort \u2013f must be used.
\n\/home\/jones $ cat flowers.txt
\nrose
\nlily
\nChrysanthemum
\ntulip
\nmarigold
\nRose
\nhibiscus
\nchrysanthemum<\/p>\n
\n\/home\/jones $ Sort flowers.txt
\nChrysanthemum
\nRose
\nChrysanthemum
\nhibiscus
\nlily
\nmarigold
\nrose
\ntulip<\/p>\n
\n\/home\/jones $ sort \u2013f flowers.txt
\nChrysanthemum
\nchrysanthemum
\nhibiscus
\nlily
\nmarigold
\nRose
\nrose
\ntulip<\/p>\n
\nA file may contain duplicate lines, and if you want to remove duplicate files before sorting , use sort \u2013u
\n\/home\/jones $ grep error cron.log
\nerror code 45:invalid time
\nerror code 35:Invalid name
\nerror code 45:invalid time
\nerror code 25:Invalid email-id
\nerror code 25:Invalid email-id
\nerror code 35 Invalid name<\/p>\n
\nerror code 25:Invalid email-id
\nerror code 35:Invalid name
\nerror code 45:invalid time<\/p>\n
\nYou require to sort based on a particular field when they are separated by a delimiter.
\n\/home\/jones $ cat detailed-list.csv
\ndolphin|mammal|12
\ngiraffe|mammal|7
\nkingfisher|aves|3
\nmoth|insecta|1
\nshark|fish|6
\nviper|reptile|2<\/p>\n
\ndolphin|mammal|12
\ngiraffe|mammal|7
\nkingfisher|aves|3
\nmoth|insecta|1<\/p>\n
\nviper|reptile|2
\nit sorted on the basis of first field (separated by \u2018|\u2019) in alphabetic order. For a change, you required to sort it based on another column.
\n\/home\/jones$ sort -t \u201c|\u201d +1 detailed-list.csv
\nkingfisher|aves|3
\nshark|fish|6
\nmoth|insecta|1
\ndolphin|mammal|12
\ngiraffe|mammal|7
\nviper|reptile|2<\/p>\n
\nmoth|insecta|1
\ndolphin|mammal|12
\nviper|reptile|2
\nkingfisher|aves|3
\nshark|fish|6
\ngiraffe|mammal|7
\nIt sorted the third column according to its alphabetic value and not arithmetic value. To do so you must use -n option<\/p>\n
\nmoth|insecta|1
\nviper|reptile|2
\nkingfisher|aves|3
\nshark|fish|6
\ngiraffe|mammal|7
\ndolphin|mammal|12<\/p>\n
\nThe sorting based on fields can be achieved using sort with \u2013k option. consider a file containing numbers.
\n\/home\/jones$ cat num-luck
\n6758 987 456
\n2586 324 934
\n0437 235 417
\n2586 324 934<\/p>\n
\n2812 624 208
\n0437 235 417
\n6758 987 456
\n2586 324 934<\/p>\n
\n2812 624 208
\n6758 987 456
\n2586 324 934
\n0437 235 417<\/p>\n
\nSort \u2013k1 \u2013k3
\nYou may require to sort a particular file and rewrite the file with the sorted file. A simple command of the form
\nSort filename >new_sorted_filename will not work and is dangerous as it rewrites it into an empty file. Use sort with \u2013o option.<\/p>\n
\nSort uses a lot of temporary space while sorting huge files. and by default it uses \/tmp directory. If sufficient space was not allocated to \/tmp, then the command would abort abruptly. so sort provides an option -T by which you can use an alternative directory for storing temporary files.<\/p>\n
\nsort -t \u201c|\u201d +1 -T \/backup\/jones detailed-list.csv.
\nthis will use \/backup\/jones directory for storing temporary files.<\/p>\n
\nsed or stream editor is an editing utility that modifies lines of a file as specified by an instruction string and writes it to standard output .sed can thus perform the same functions of the commands like tr, grep and awk ,even though sed has functionalities and options unique to itself.
\nThough the applications of sed are enormous, only some of the important uses of the command are discussed here with examples.
\nExample 1)
\nIt is required to you to print the contents of a file starting from a particular line number and ending into another ,use sed as follows.
\n\/home\/UAT$ sed -n \u201835,46p\u2019 general-dates.prt
\nThis command prints the contents of the file \u201cgeneral-dates.prt \u201c starting from its 35th line to the 46th.
\nTo print only the 35th line of a file use
\n\/home\/UAT$ sed -n \u201835p\u2019 general-dates.prt
\nMore examples
\n\u00b7 To print all the lines of a file starting from its 1st line to the last line
\n sed -n \u20181,$p\u2019 general-dates.prt
\n\u00b7 To print all the lines of a file between line numbers whose values are stored in variables $start-line and $end-line .
\nsed \u2013n \u201c${start-line} , ${end-line}p\u201d general-dates.prt
\n\u00b7 To print all the lines of the file except the 5th line
\nsed \u20185d\u2019 general-dates.prt
\n\u00b7 To print all the lines of the file except those lines between the 8th and the 40th (i.e. 8th line and 40th lines are also not printed).
\nsed \u20188,40d\u2019 general-dates.prt<\/p>\n
\nsed can also search for patterns in file or standard input just like grep , but much more sophisticated pattern searches can be done as shown in the following examples.
\n\u00b7 A grep command can be implemented using sed as follows
\nConsider a grep command
\ngrep industry general-dates.prt
\nalternatively sed can perform the same using..
\nsed \u2013n \u2018\/industry\/p\u2019 general-dates.prt<\/p>\n
\n sed \u2013n \u2018\/industry\/,\/station\/p\u2019 general-dates.prt<\/p>\n
\n sed \u2013n \u20181,\/ industry\/p\u2019 general-dates.prt<\/p>\n
\nsed can replace the occurrences of patterns into a new one from a file and put it to standard output.
\n\u00b7 To replace the first occurrence of \u2018teacher\u2019 with \u2018tutor\u2019 in the file groupsList.xml
\nsed \u2018s\/ teacher\/ tutor\/\u2019 groupsList.xml
\n\u00b7 To replace all the occurrences of \u2018teacher\u2019 with \u2018tutor\u2019 in the file groupsList.xml
\nsed \u2018s\/ teacher\/ tutor\/g\u2019 groupsList.xml
\nhere g -> represents global.
\n\u00b7 To replace all the occurrences of a string stored in a variable ${string_pattern} to ${replace_string} in a file.
\nsed \u2018s\/\u2019${string_pattern}\u2019\/\u2019 ${replace_string}\u2019\/g\u2019 groupsList.xml<\/p>\n
\nsed \u2018s\/\u2019${string_pattern}\u2019\/&,\u2019${ replace_string }\u2019\/g\u2019 groupsList.xml
\nthe single quotes enclosing the variable is a necessary.
\n& variable stores the matched pattern when the string stored in ${string_pattern} is a regular expression.<\/p>\n
\nSed can be used to edit a particular line of the file. amazing..isnt it..?
\n\/home\/UAT$ cat dir_struct
\n1. 35467 vdn \/home\/vd2
\n2. 46788 ghi \/var\/gh1\/gh
\n3. 89078 bjk \/home\/vd2
\n4. 56890 lod \/home\/lod\/inter
\n5. 33456 bhj \/home\/bhind
\n6. 45790 krk \/myhome\/krk<\/p>\n
\n1. 35467 vdn \/home\/vd2
\n2. 46788 ghi \/var\/gh1\/gh
\n3. 89078 bjk \/home\/vd2
\n4. 56890 lod \/var\/lod\/inter
\n5. 33456 bhj \/home\/bhind
\n6. 45790 krk \/myhome\/krk<\/p>\n
\nsed \u20184 s\/\\\/home\\\/vd2\/\\\/var\\\/vd1\/\u2019 dir_struct
\nlooks a little ugly because we used \u2018\/ \u2018 as delimiter and to differentiate the \u2018\/\u2019 in \/home\/vd2 and \/var\/vd1, a backslash \u201c\\\u201dwas used before it.
\ninstead of using \u2018\/\u2019as delimiter other characters like : , | , { , # , ! etc can be used for such scenarios.
\nThe above sed can be written using # as follows.<\/p>\n
\nYou have many occurrences of a pattern in a line and you want to replace just the nth pattern or all n+1,n+2.. occurrences . use a number after the ending \u201c\/\u201d.
\n\/home\/jade$ echo “1st 2nd 3rd 4th 5th 6th”|sed “s\/[0-9]th\/\/2”
\n1st 2nd 3rd 4th 6th # |—–second occurrence of [0-9]th<\/p>\n
\nIf you need to replace all occurrences starting from 2nd,then use the following command.<\/p>\n
\n“1st 2nd 3rd 4th ”<\/p>\n
\nThe rsh command executes the command or a program in another host from current working machine without having to login into that remote machine by entering a password as in ssh. You can run any unix command, or a shell script of a remote host.<\/p>\n
\nrsh command cannot be executed without making these changes.<\/p>\n
\n158.0.125.23 mahaprana #backup server.<\/p>\n
\nSimilarly make an entry of remote host In \/etc\/hosts file of local host. If remote hostname is alpaprana and its IP address is 158.0.125.45 .
\n158.0.125.45 alpaprana<\/p>\n
\nEg: If the local users are divya and ajay and remote users are bhaskar and ajay.
\n.
\nMake entries as shown for respective users in local host
\n\/home\/ divya$ hostname
\nmahaprana
\n\/home\/ divya$ echo $HOME
\n\/home\/ divya
\n\/home\/ divya$ cat .rhosts
\n158.0.125.45 bhaskar
\n158.0.125.45 ajay<\/p>\n
\n\/home\/ajay
\n\/home\/ ajay$ cat .rhosts
\n158.0.125.45 bhaskar
\n158.0.125.45 ajay<\/p>\n
\nalpaprana
\n\/home\/ ajay$ cat $HOME\/.rhosts
\n158.0.125.23 ajay
\n158.0.125.23 divya<\/p>\n
\n158.0.125.23 ajay
\n158.0.125.23 divya<\/p>\n
\nSuppose you are working as a user in local host and the local and remote users are same.
\n\/home\/ ajay$ echo $LOGNAME
\najay
\n\/home\/ ajay$ rsh 158.0.125.45 \u201cls inter*\u201d
\ninterbranch.csv.gz
\ninterschool.csv.gz
\ninter _college.txt
\ninter-dept.lst<\/p>\n
\nBy default it runs the commands within double quotes in user (ajay ) \u2018s home directory defined by the $HOME variable.<\/p>\n
\nTo run the commands or process of a different remote user<\/p>\n
\nHere comes the sun – BEATLES
\nBeatles-Twist and shout<\/p>\n
\nEg: If you want to run the above command by making your working directory as Albumlist\/old
\nrsh 158.0.125.45 -l bhaskar \u201c cd Albumlist\/old; grep -i beatles Film\u201d .
\nExample 3)
\nyou cannot use the environmental variables of the remote user directly inside rsh. For initializing all those variables run .profile<\/p>\n
\nksh: sqlplus not found
\n this did not work.
\n\/home\/ ajay$ rsh 158.0.125.45 -l bhaskar \u201c. $HOME\/.profile 1> \/dev\/null; echo $ORACLE_HOME; sqlplus \/\u201d
\n\/oracle\/app\/product
\nSQL>
\n\/dev\/null redirects the standard output of running .profile to \/dev\/null.<\/p>\n
\nTo remove multiple files with a common keyword.<\/p>\n
\nCity_DETAIL_MUM.lst
\nCity_DETAIL_DEL.lst
\nCity_DETAIL_BLR.lst
\nCity_DETAIL_KOL.lst
\nCity_DETAIL-ALL
\n..
\nTo remove all these files except City_DETAIL-ALL enter
\n\/home\/jenny$rm City_DETAIL_???.lst<\/p>\n
\nrm command asks you before removing ,i:e<\/p>\n
\nTo remove directories and files use \u2013rf option
\n\/home\/jenny$rm -rf FILMS
\nThis will remove all the sub directories of and the directory itself. This command is also same as
\ncd \/; rm \u2013rf home\/jenny\/FILMS<\/p>\n
\neg: both of these don\u2019t work.<\/p>\n
\n\/home\/jenny \/FILMS\/K3g$rm -rf \/home\/jenny \/FILMS #Does not work<\/p>\n
\n\/home\/jenny$ head file_to_remove_list
\nJj12_2.txt
\nDf003.log
\nAwer_cat.lst
\nSdifre.post
\nMail34.log
\nTAB\/Hourwise_list.doc
\nSequence.log
\nCreated\/Sqlldr.bad
\nOLD_FILE\/Jenny_old.log
\nHearts_jai.mkv<\/p>\n
\nhome\/jenny$chmod +x file_to_remove_list.sh
\n\/home\/jenny$.\/ file_to_remove_list.sh
\nremoving Jj12_2.txt
\nremoving Df003.log
\nremoving Awer_cat.lst
\nremoving Sdifre.post
\nremoving Mail34.log
\nremoving TAB\/Hourwise_list.doc
\nremoving Sequence.log
\nremoving Created\/Sqlldr.bad
\nremoving OLD_FILE\/Jenny_old.log
\nremoving Hearts_jai.mkv
\n\/home\/jenny$<\/p>\n
\nTo remove files interactively use -i option.
\n\/home\/jenny$ rm -ir FILMS
\nrm: remove FILMS\/ Schindler’s List ?y
\nrm: remove FILMS\/ Chinatown? y
\nrm: remove FILMS\/ Taxi Driver?y
\nrm: remove FILMS\/ The Sixth Sense?n
\n\/home\/jenny$<\/p>\n
\nrcp is used to copy or send files or directories between two hosts. It can be used an alternative to ftp and related protocols like sftp, but no password is required to send files unlike ftp.
\nFor rcp to work, various prerequisites are required ,which are same for the rsh command.(refer rsh)<\/p>\n
\nTest-serv and IP is 192.158.0.120 .The local user is kumar and remote user is warren in all of the examples.<\/p>\n
\nTo send a file from a local host to remote host.<\/p>\n
\nWith the name Audit_document.txt and owner of the file as warren.<\/p>\n
\nTo receive a file from remote host to local host.
\n\/home\/kumar$ rcp warren@192.158.0.120:global\/Meal_pass2.prt .
\nThis copies the file Meal_pass2.prt in \/home\/warren\/global directory of 192.158.0.120
\nto the current directory (\/home\/kumar denoted here by \u2018.\u2019 or dot).<\/p>\n
\nTo copy directories between hosts use rcp with \u2013r option.<\/p>\n
\ndrwxr-xr-x 2 kumar tools 256 Jul 14 2009 localdir<\/p>\n
\nThis copies the entire directory localdir(its sub directories) to $HOME directory of warren@192.15.0.120.<\/p>\n
\nTo copy two files booked_ticket1.txt , booked_ticket2.txt to \/var\/docs directory of 192.15.0.120
\nrcp booked_ticket.txt booked_ticket2.txt warren@192.15.0.120: \/var\/docs
\nor
\nrcp booked_ticket?.txt warren@192.15.0.120: \/var\/docs<\/p>\n
\nrcp -p pattern-styles.tar.gz warren@192.15.0.120: images\/style1.tar.gz<\/p>\n
\nps displays all the processes in a unix system. every command, script or an application is considered as a process in unix. All the processes run until the command or application is completed or stopped. Each process has a unique process id ( PID)
\nIt has the same output of windows tasklist command.
\nExample 1)
\nto list only your processes (i:e all the commands , and applications run in current session )
\n\/home\/priya$ ps
\n PID TTY TIME CMD
\n 217140 pts\/2 0:00 -ksh
\n 594062 pts\/2 0:00 -ksh
\n 652138 pts\/2 2:03 java webfile.java
\n 820120 pts\/2 0:00 ps<\/p>\n
\nTo list all the processes running in the server page wise , use \u2013ef option
\n\/home\/priya$ ps -ef | pg
\n UID PID PPID C STIME TTY TIME CMD
\npriya 184434 1 24 05:32:34 – 0:50 java \/usr\/bin\/java\/start-web.java
\nroot 213146 1 0 05:32:31 – 1:21 java \/usr\/bin\/dsmc
\nmatt 327814 893836 0 12:28:09 – 0:00 sleep 120
\nroot 352266 1 0 05:32:38 – 0:14 java \/usr\/bin\/ftpd
\npriya 368734 1 0 05:32:42 – 0:07
\npriya 372912 1 0 05:32:43 – 0:10 java \/usr\/bin\/java\/start-web3.java
\nscripts 409806 1 0 05:32:39 – 0:13 java \/usr\/bin\/java\/start-web2.java -d final -f clear
\nscripts 418030 1 0 05:32:35 – 1:08 java \/usr\/bin\/java\/start-web.java -d final -f clear
\nscripts 430084 1 0 05:32:23 – 0:02 \/usr\/bin\/perl -w getfile.cgi
\nscripts 442592 430084 0 12:17:38 – 0:00 sleep 900
\nscripts 454810 1 3 05:32:29 – 1:42 java \/usr\/bin\/java\/start-web.java -d final -f clear
\nstandard input<\/p>\n
\nTo list all the processes which are run by an user,
\n\/home\/priya$ ps -fu matt
\nUID PID PPID C STIME TTY TIME CMD
\nmatt 174431 1 24 05:32:34 – 0:50 wc -l
\nmatt 723156 1 0 05:32:31 pts\/2 1:21 cat items
\nmatt 327814 893836 0 12:28:09 – 0:00 sleep 120
\nmatt 1566 1 0 0 5:32:38 pts\/1 0:14 sed \u2018s\/sim\/\/\u2019
\nmatt 668739 1 0 05:32:42 – 0:07 \/usr\/bin\/perl
\nmatt 352912 1 0 05:32:43 – 0:10 java hello.java<\/p>\n
\nPID
\nThe process ID of the process.<\/p>\n
\nThe user ID of the process owner. The login name is printed under the -f flag.<\/p>\n
\nThe process ID of the parent process.<\/p>\n
\nCPU utilization of process or thread, incremented each time the system clock ticks and the process or thread is found to be running. Large values indicate a CPU intensive process and result in lower process priority whereas small values indicate an I\/O intensive process and result in a more favourable priority.<\/p>\n
\nThe starting time of the process.<\/p>\n
\nThe controlling terminal for the process
\nif There is a \u2018-\u2018 ,it means the process is not associated with a terminal.
\nOtherwise indicates The TTY number. For example, the entry pts\/2 indicates terminal 2.<\/p>\n
\nContains the command name which started the process. The full command name and its parameters are displayed with the -f flag.<\/p>\n
\npaste is an excellent command for text processing, even though its uses are limited. It can mainly be used to append the contents of files. paste is helpful in creating text files by combining
\nindividual files such that all the lines appear on the same row in the destination file i:e linearly.<\/p>\n
\nYou have two files as shown.
\n\/users\/higgs$ cat Start_Times.log
\nGetname( ) at Fri Dec 30 22:29:16 IST 2011
\nGetip( ) at Fri Dec 30 22:30:22 IST 2011
\nCheckip( ) at Fri Dec 30 22:30:23 IST 2011
\nGetfile( ) at Fri Dec 30 22:31:22 IST 2011<\/p>\n
\nGetname( ) at Fri Dec 30 22:29:17 IST 2011
\nGetip( ) at Fri Dec 30 22:30:28 IST 2011
\nCheckip( ) at Fri Dec 30 22:30:24 IST 2011
\nGetfile( ) at Fri Dec 30 22:31:42IST 2011<\/p>\n
\nGetname( ) at Fri Dec 30 22:29:16 IST 2011 Getname( ) at Fri Dec 30 22:29:17 IST 2011
\nGetip( ) at Fri Dec 30 22:30:22 IST 2011 Getip( ) at Fri Dec 30 22:30:28 IST 2011
\nCheckip( ) at Fri Dec 30 22:30:23 IST 2011 Checkip( ) at Fri Dec 30 22:30:24 IST 2011
\nGetfile( ) at Fri Dec 30 22:31:22 IST 2011 Getfile( ) at Fri Dec 30 22:31:42IST 2011<\/p>\n
\nis default for paste without any option.<\/p>\n
\n\/users\/higgs$ cat Start_end_times.csv
\nGetname( ) at Fri Dec 30 22:29:16 IST 2011, Getname( ) at Fri Dec 30 22:29:17 IST 2011
\nGetip( ) at Fri Dec 30 22:30:22 IST 2011 , Getip( ) at Fri Dec 30 22:30:28 IST 2011
\nCheckip( ) at Fri Dec 30 22:30:23 IST 2011 , Checkip( ) at Fri Dec 30 22:30:24 IST 2011
\nGetfile( ) at Fri Dec 30 22:31:22 IST 2011 ,Getfile( ) at Fri Dec 30 22:31:42IST 2011<\/p>\n
\nIf you want the contents to appear serially,use paste \u2013s.<\/p>\n
\n\/users\/higgs$ cat Booked.log
\nDon2
\nSherlock_homes
\nMission_Impossible4
\nThe_Dirty_picture<\/p>\n
\n10:30
\n14:20 4 spaces after each line
\n17:40
\n22:45 <\/p>\n
\n10:30 14:20 17:40 22:45<\/p>\n
\nmv command moves or renames files or directories within the same file system or between different file systems. you can also do this interactively when you are moving multiple files.mv is similar to doing cut and paste in windows,<\/p>\n
\nTo rename a file or a directory.
\n\/home\/yogi$mv yog_LIST jeev_LIST<\/p>\n
\nSimilarly a directory can be renamed. <\/p>\n
\nTo move a file to a directory.
\n\/home\/yogi$mv sqlnet.log oracle_logs<\/p>\n
\nmv sqlnet.log oracle_logs\/sqlnet_2011.log
\nIn this case sqlnet.log is renamed to sqlnet_2011.log and saved in oracle_logs directory.<\/p>\n
\nA file,directory or a group of files or directories can be moved to a
\ndestination path,<\/p>\n
\n-rw-r–r– 1 yogi Administ 58 Dec 24 00:40 CONSIGNMENT1
\n-rw-r–r– 1 yogi Administ 6 Dec 24 00:42 CONSIGNMENT2
\n-rw-r–r– 1 yogi Administ 978 Dec 25 00:59 CONSIGNMENT3 <\/p>\n
\n-rw-r–r– 1 yogi Administ 27 Jul 25 01:00 lst2.txt
\n-rw-r–r– 1 yogi Administ 35 Sep 14 09:00 goods_list<\/p>\n
\nmv: cannot rename CONSIGNMENT* to \/ALL_CONS\/DOCS, a file or directory in the path does not exist.<\/p>\n
\nIf you want mv to ask you interactively which files are to be moved, use mv \u2013i.
\n\/home\/yogi$ mv -i Banks_Draft * DRAFTS\/LIST <\/p>\n
\ncontents of the page are displayed as the user examines them and wishes to go
\nto the next one. user can use various keys in order to go front or back of a page. Move
\nto few lines ahead or behind.<\/p>\n
\nsuppose you have a large file with name greenlife.txt. It contains a total of 1000 lines.<\/p>\n
\n\/home\/g321$ more greenlife.txt
\nsustainable living
\nSustainable living is a lifestyle that attempts to reduce an individual’s or soceity\u2019s
\nattempt to reduce their carbon footprint by altering methods of transportation, energy
\n sustainability, in natural balance and respectful of humanity’s symbiotic relaivelyt
\nly interrelated with the overall principles of sustainable development.
\nLester R. Brown, a prominent environmentalist and founder of the Worldwatch Inst used
\n reuse\/recycle economy with a diversified transport system.”
\nContents
\n1 Definition
\n2 History
\n3 Shelter
\n3.1 List of some sustainable materials
\n4 Power
\n4.1 List of organic matter than can be burned for fuel
\n5 Food
\n5.1 Environmental impacts of industrial agriculture
\n5.2 Conventional food distribution and long distance transport
\n5.3 Local and seasonal foods
\n5.4 Reducing meat consumption
\n5.5 Organic farming
\n5.6 Urban gardening
\n5.7 Food preservation and storage
\n6 Transportation
\n7 Water
\n7.1 Indoor home appliances
\n7.1.1 Toilets
\n7.1.2 Showers
\n7.1.3 Dishwasher\/Sinks
\n7.1.4 Washing machines
\n7.2 Outdoor water usage
\n7.2.1 Conserving Water
\n7.2.2 Sequestering Water
\n8 Waste
\nSustainable living is fundamentally the application of sustainability to lifestyle
\n— More (3%) —
\nHere it waits for user input to go to the next page. The user now has the choice of doing the following few things.(many more options available)
\nto display the next line ,type return or \u201cEnter\u201d key. type f to go
\nfront 1 line and b to go back one line.
\nto display the entire next page type space key.
\nTo go 100 lines ahead type 100f and press enter
\nTo go 10 lines behind type 10b
\n To go to the end of page press shift + g
\nTo exit press q
\nTo search a pattern, type \/and enter the keyword.<\/p>\n
\nWhile searching for patterns using more , if you want to ignore cases use \u2013i option.
\n\/home\/g321$ more greenlife.txt
\n…
\n….
\n…… lines
\n\/outdoor
\n|
\n|
\n—— >This will search for all the occurrences of the pattern \u2018outdoor\u2019 in the file, ignoring case and highlights them.<\/p>\n
\nYou can cause more command to display the specified number of lines in the window by using \u2013n number option.
\nFor example to view 15 lines per window ,<\/p>\n
\nmkdir is used to create one or more directories. It can create entire directory structure if needed, or can give required permissions to a directory.<\/p>\n
\n\/home\/MUM-user$ mkdir channels
\nyou further want to create directory structures. The conventional method of doing it would be
\n\/home\/MUM-user$cd channels
\n\/home\/MUM-user\/ channels$mkdir STAR
\n\/home\/MUM-user\/ channels$mkdir SONY
\n\/home\/MUM-user\/ channels$cd SONY
\n\/home\/MUM-user\/ channels\/ SONY$mkdir KBC
\n\u2026.
\n\u2026..
\ni:e create all the individual directories in the tree.
\nmkdir provides an option \u2013p to help you to avoid these commands.<\/p>\n
\n\/home\/MUM-user$ mkdir -p channels\/ SONY\/ KBC<\/p>\n
\nTo change permissions to directories, you can use chmod command. To do it while creating them, use mkdir -p
\n\/home\/MUM-user\/ $ls \u2013ld channels\/discovery
\ndrwxrwxr-x 2 MUM-user Tools 256 NOV 12 22:01 channels\/discovery<\/p>\n
\nMan command internally invokes the sed command to modify the contents of manual pages(documentation written for the commands) and delivers a user readable output.
\nExamples:
\nExample 1:
\nTo read documentation on sed command page-wise
\n\/home\/b3456\/$ man sed | pg<\/p>\n
\nsuppose that you want to read the entire documentation of all the commands present in an unix environment and to save all of its pages in a single text file, you can run the following script from the command line to do so.
\n\/home\/b3456\/$ cd \/usr\/bin
\n\/usr\/bin\/$for i in `ls * `
\n>do
\n>man $i >>\/home\/b3456\/man_all.txt 2>\/dev\/null
\n>done
\nNote: \u201c>\u201d symbol comes by default in all the lines
\nHere 2> indicates standard error.It is redirected to \/dev\/null(which is discarded)
\nNow you can take a print out of the text file you have just generated( make full use of office printer umm!!) and study all commands at home.<\/p>\n
\nls command is used to list the contents off the directory.ls writes to standard output
\nall the information of the files, directories or specifically of the parameters passed to it.
\nYou can display these contents in the alphabetically sorted order, or list only particular files in
\nCombination with other command. There are many options with ls which you may hardly use in normal cases.
\nHere ,only few frequently used options are discussed.<\/p>\n
\nTo simply display the names of all the files in a directory.
\n\/home\/script-user$ ls
\nJoke-and-fun.xt
\nSend_script.sh
\nMail-file
\nRollercoaster
\nJackson_note.tar<\/p>\n
\nTo display all the files that have a common pattern.
\n\/home\/script-user\/items $ ls table_*.log
\ntable_111.log
\ntable_x.log
\ntable_te1.log
\ntable_adam.log<\/p>\n
\n To get a long listing of files which contains all the details such as file size, permissions,
\nTime stamp, user details sorted by the modification time, use ls as follows.<\/p>\n
\n-rw-r–r– 1 script-user Tools 56344 Dec 16 14:37 Joke-and-fun.xt
\n-rw-r–r– 1 script-user Tools 105977 Dec 16 15:52 Send_script.sh
\n drw-r–r– 2 script-user Tools 256 Dec 18 21:01 Mail-file
\n-rw-r–r– 1 script-user Tools 740 Dec 20 01:03 Rollercoaster
\n-rw-r–r– 1 script-user Tools 58 Dec 24 00:40 Jackson_note.tar<\/p>\n
\n2nd field is the type of element,(1 for file 2 for directory..etc)
\n3rd field gives the owner of the element(file,directory)
\n4th field gives the group which the user belongs to.
\n5th field gives the size.
\n6th,7th and 8th field-modification times.
\n9 th field gives the name of the element.<\/p>\n
\nFor eg: To get the name of the element from the output of ls \u2013lrt, use awk as follows
\n\/home\/script-user $ ls -lrt | awk \u2018{print $9}\u2019
\nJoke-and-fun.xt
\nSend_script.sh
\n Mail-file
\nRollercoaster
\nJackson_note.tar
\nExample 4)
\nTo display only the directories in a path, use the output of ls \u2013lrt as follows.
\n\/home\/script-user $ ls -lrt | grep \u201c^d\u201d
\n drw-r–r– 2 script-user Tools 256 Dec 18 21:01 Mail-file<\/p>\n
\nIn this case grep searched for the lines starting with a \u2018d\u2019 which stands for directories.<\/p>\n
\n you want to list the directories whose name has a common pattern, use ls \u2013ld
\ndrwxr-xr-x 2 script-user Tools 256 Nov 9 12:10 j2me
\ndrwxr-xr-x 2 script-user Tools 20480 Nov 9 12:10 java
\ndrwxr-xr-x 2 script-user Tools 4096 Nov 9 12:10 java scripts<\/p>\n
\nTo make a case insensitive list on a filename parameter, use ls along with grep as follows.
\nhome\/script-user\/docs$ ls report*
\nreport1.doc
\nreport_eng.doc
\nreportslist.txt<\/p>\n
\n report1.doc
\nreport_eng.doc
\nreportslist.txt
\nReports_Bulk.wrt
\nBusiness_reports.doc<\/p>\n
\nTo list all the directories in a directory, and its subdirectories, use ls \u2013R
\nIn this case ls lists all the files inside the directories starting with j recursively in all its subdirectories.
\nhome\/script-user\/ebooks $ ls -R j*
\nj2me:
\nj2me – the complete reference.pdf j2me—the-complete-reference.htm<\/p>\n
\nby using kill -l (lowercase alphabet L).<\/p>\n
\nSIGHUP 1 hangup, generated when terminal disconnects
\nSIGINT 2 interrupt, generated from terminal special char
\nSIGQUIT 3 (*) quit, generated from terminal special char
\nSIGILL 4 (*) illegal instruction (not reset when caught)
\nSIGTRAP 5 (*) trace trap (not reset when caught)
\nSIGABRT 6 (*) abort process
\nSIGEMT 7 EMT instruction
\nSIGFPE 8 (*) floating point exception
\nSIGKILL 9 kill (cannot be caught or ignored)
\nSIGBUS 10 (*) bus error (specification exception)
\nSIGSEGV 11 (*) segmentation violation
\nSIGSYS 12 (*) bad argument to system call
\nSIGPIPE 13 write on a pipe with no one to read it
\nSIGALRM 14 alarm clock timeout
\nSIGTER M 15 software termination signal
\nSIGURG 16 (+) urgent condition on I\/O channel
\nSIGSTOP 17 (@) stop (cannot be caught or ignored)
\nSIGTSTP 18 (@) interactive stop
\nSIGCONT 19 (!) continue (cannot be caught or ignored)
\n SIGCHLD 20 (+) sent to parent on child stop or exit
\n SIGTTIN 21 (@) background read attempted from control terminal
\n SIGTTOU 22 (@) background write attempted to control terminal
\n SIGIO 23 (+) I\/O possible, or completed
\n SIGXCPU 24 cpu time limit exceeded
\n SIGXFSZ 25 file size limit exceeded
\n SIGMSG 27 input data is in the ring buffer
\n SIGWINCH 28 (+) window size changed
\n SIGPWR 29 (+) power-fail restart
\n SIGUSR1 30 user defined signal 1
\n SIGUSR2 31 user defined signal 2
\n SIGPROF 32 profiling time alarm
\n SIGDANGER 33 system crash imminent; free up some page space
\n SIGVTALRM 34 virtual time alarm
\n SIGMIGRATE 35 migrate process
\n SIGPRE 36 programming exception
\n SIGVIRT 37 AIX virtual time alarm
\n SIGALRM1 38 m:n condition variables – RESERVED – DON’T USE
\n SIGTALRM 38 per-thread alarm clock
\n SIGWAITING 39 m:n scheduling – RESERVED – DON’T USE
\n SIGRECONFIG 58 Reserved for Dynamic Reconfiguration Operations
\n SIGCPUFAIL 59 Predictive De-configuration of Processors \u2013 (RESERVED – DON’T USE ) <\/p>\n
\n SIGGRANT SIGKAP monitor mode granted
\n SIGRETRACT 61 monitor mode should be relinquished
\n SIGSOUND 62 sound control has completed
\n SIGSAK 63 secure attention key <\/p>\n
\nYou can stop a running process in the midway and then continue it from that point using kill command.
\nAssume you are running a ftp command and want to stop the file transfer.
\n\/home\/b6789$ ftp 10.42.67.125
\n\u2026\u2026
\n\u2026\u2026.
\nput abigfile.txt
\n#####################################<\/p>\n
\nkill -17
\nKill -19
\nTo Kill all the child processes of a particular process use
\nkill -9 –
\nkill -9 -204567<\/p>\n
\nhead command is used to view or save a specified portion of the beginning of a file.
\nIt does the same work as tail does for the end of the file.<\/p>\n
\nHead by default displays first 10 lines of a file when no option is specified.
\n\/home\/ftpusr$ head blackwater.ns
\nBlackwater USA was formed in 1997, by Erik Prince in North Carolina, to provide training support to military and law enforcement organizations. In explaining the Blackwater’s purpose, Prince stated that \u2018\u2018We are trying to do for the national security apparatus what FedEx did for the Postal Service.\u2019\u2019After serving SEAL and SWAT teams, Blackwater USA received their first government contract after the bombing of the USS Cole off of the coast of Yemen in October of 2000. After winning the bid on the contract, Blackwater was able to train over 100,000 sailors safely.Prince purchased about 7,000 acres (28 km2) (from Dow Jones Executive, Sean Trotter) of the Great Dismal Swamp, a vast swamp on the North Carolina\/Virginia border, now mostly a National Wildlife Refuge. “We needed 3,000 acres to make it safe,” Prince told reporter Robert Young Pelton.There, he created his state-of-the-art private training facility and his contracting company, Blackwater, which he named for the peat-colored water of the swamp. The The Blackwater Lodge and Training Center officially opened on May 15, 1998 with a 6,000 acre facility and cost $6.5 million.<\/p>\n
\n\/home\/ftpusr$ head -2 blackwater.ns
\nBlackwater USA was formed in 1997, by Erik Prince in North Carolina, to provide training support to military and law enforcement organizations. In explaining the Blackwater’s purpose, Prince stated that \u2018\u2018We are trying to do for the<\/p>\n
\nwhen you have a very large file(say of 100000 lines) and it is difficult to open such a file in vi, but you are concerned only with first few lines of the file.
\nIn that case redirect the first few lines of that huge file into another file and open that file in vi.<\/p>\n
\n\/home\/ftpusr$vi migratory_note_1000
\n..
\n..<\/p>\n
\nIn scripts, there are times where you initialize the output of grep to a variable but grep searches and returns multiple values, you can use only the first returned value by head -1,
\nConfused..?the example below shows how.<\/p>\n
\n\/home\/ftpusr$b=`grep 7 prime_numbers`
\n\/home\/ftpusr$echo $b
\n7
\n17
\n37<\/p>\n
\nUse head as follows.
\n\/home\/ftpusr$b=` grep 7 prime_numbers | head -1`
\n\/home\/ftpusr$echo $b
\n7<\/p>\n
\nTo print the nth line of a file, use head and tail in combination as follows.<\/p>\n
\nThis prints 100th line of the file.<\/p>\n
\ngzip is used to compress files and tar is used to archive a file system. Though these two are different commands ,using them together can accomplish a variety of tasks which seem to be
\nmuch simpler than when running them separately. Here we will also discuss about the combined use of tar and cd commands.<\/p>\n
\ngzip<\/p>\n
\ngzip is a compression utility that uses Huffman coding to compress files and save them in .gz format . The .gz file occupies lesser space than the original file. We will not discuss about the .gz file format , but only show how the command can be used along with its options.<\/p>\n
\n\/home\/gr-adm $ ls \u2013lrt stake-holder.csv*
\n-rw-r–r– 1 gr-adm Administ 56344 Dec 16 14:37 greenlife.txt<\/p>\n
\n\/home\/gr-adm$ l s -lrt stake-holder.csv*
\n-rw-r–r– 1 kaushik Administ 20758 Dec 16 14:37 greenlife.txt.gz<\/p>\n
\nIf you want to retain the original file even after compression or want the .gz file to have a different name, use gzip \u2013c.<\/p>\n
\ngzip -c stake-holder.csv >>\/backup\/stakes\/Old-stake-holder.csv.gz<\/p>\n
\nTo decompress the .gz file use gunzip
\n\/home\/gr-adm$ gunzip \/backup\/stakes\/stake-holder.csv.gz
\nThis command will decompress the file stake-holder.csv.gz and places the original file
\nstake-holder.csv in \/backup\/stakes\/ itself.<\/p>\n
\nTo view the contents of the file without completely decompressing the file , use gzip \u2013dc.
\nUse pg command to view it pagewise..
\n\/home\/gr-adm$ gzip -dc stake-holder.csv.gz | pg
\nA premji, wipro,67
\nN R murthy,Infosys,65
\nN Chandra,TCS,46
\n…
\n..
\nYou can redirect the output into another file,
\nFor eg to redirect first 5 lines of the file stake-holder.csv.gz ,<\/p>\n
\nTo create a tar file of a directory structure and to view the progress of tar use,<\/p>\n
\na data\/notes\/Nov-10\/exceptions.txt 200 bytes
\na data\/notes\/Nov-12\/promotions.csv 123 bytes
\na data\/notes\/N0v-13\/oracle-log\/ora-errors.log 456 bytes
\na data\/notes\/tea-time.in 2076 bytes
\na data\/notes\/network\/virtual-ips.bmp 1290bytes
\na data\/notes\/levy.list 87bytes
\n\/home\/gr-adm $<\/p>\n
\nTo extract the contents of the archive file into a different location , first change your working directory to the location where you wish to extract the file, then extract and view the progress by running tar with \u2013xvf switch.<\/p>\n
\n\/home\/gr-adm$ tar -xvf \/archives\/archive2\/data-history.tar
\nx data\/notes\/Nov-10\/exceptions.txt 200 bytes
\nx data\/notes\/Nov-12\/promotions.csv 123 bytes
\nx data\/notes\/N0v-13\/oracle-log\/ora-errors.log 456 bytes
\nx data\/notes\/tea-time.in
\nx data\/notes\/network\/virtual-ips.bmp
\nx data\/notes\/levy.list
\n\/home\/gr-adm $<\/p>\n
\nInstead of giving entire directory name as a parameter to create a tar file, a list of files which care to be archived can be can be passed to tar with \u2013L option.
\nA file containing the list of files to take tar is as shown.
\n\/home\/gr-adm$ cat to-tar-list
\ndata\/notes\/Nov-10\/exceptions.txt
\ndata\/notes\/N0v-13\/oracle-log\/ora-errors.log
\ndata\/notes\/levy.list<\/p>\n
\na data\/notes\/Nov-10\/exceptions.txt 200 bytes
\na data\/notes\/N0v-13\/oracle-log\/ora-errors.log 456 bytes
\na data\/notes\/levy.list 87 bytes<\/p>\n
\nSometimes you may need to exclude files from the tar archive. To do this place the files and directories to be excluded in a list file and then use tar \u2013X
\ndata\/notes\/Nov-10\/exceptions.txt
\ndata\/notes\/Nov-12\/promotions.csv
\ndata\/notes\/N0v-13\/oracle-log\/ora-errors.log <\/p>\n
\na data\/notes\/tea-time.in 2076 bytes
\na data\/notes\/network\/virtual-ips.bmp 1290bytes
\na data\/notes\/levy.list 87bytes<\/p>\n
\nThe contents of the tar file cannot be viewed directly by cat or more , but to view the details of the files and directories contained in the tar file ,use tar \u2013tvf<\/p>\n
\n-rw-r–r– gr-adm 2076 2011-12-16 15:52:55 data\/notes\/tea-time.in
\n-rw-r–r– gr-adm 1290 2011-12-30 22:44:59 data\/notes\/network\/virtual-ips.bmp
\n-rw-r–r– gr-adm 87 2011-12-30 22:45:48 data\/notes\/levy.list <\/p>\n
\n gzip -dc data_archive.tar.gz – | rsh 10.198.150.45 -l fnsonlad “cd \/archives\/archive2;tar xvf \u2013\u201c<\/p>\n
\nfind command helps you to find files in a directory structure much faster than ls command for
\nvarious options. It can widely be used for getting the list of files in a directory and its sub directories
\nwith a given condition on file time stamp, size, name and so on.<\/p>\n
\nParticular path, then use the find command as follows.
\n \/home\/Varsha $ find . \u2013type d
\n.\/ebooks\/perl
\n.\/ebooks\/perl\/1.Strings
\n.\/ebooks\/perl\/10.Subroutines
\n.\/ebooks\/perl\/11.Ref and REcs
\n.\/ebooks\/perl\/12.Packages, Libraries, and Modules
\n.\/ebooks\/perl\/13.Classes, Objects, and Ties
\n.\/ebooks\/perl\/14.Database Access
\n.\/songs\/hindi\/songs collection\/15 jab we met
\n.\/songs\/hindi\/songs collection\/1942 A Love Story
\n.\/songs\/hindi\/songs collection\/20 hey baby
\n.\/songs\/hindi\/songs collection\/22 jhoom barabar jhoom
\n.\/.\/songs\/hindi\/songs collection\/26 let the music play 3++
\n.\/songs\/hindi\/songs collection\/Aa Dekhe Zara
\n.\/songs\/hindi\/songs collection\/Aap Kaa Suroor
\n.\/songs\/hindi\/songs collection\/Aashiq Banaya Aap Ne
\n.\/songs\/hindi\/songs collection\/Rockstar
\n.\/songs\/hindi\/songs collection\/3 idiots
\n.
\n.
\n.
\n.
\n ^C
\nIt seems varsha listens to these songs while her boss is not around .<\/p>\n
\nSimilarly for displaying all the files you can use -type f option. Here the \u2018.\u2019 In the command refers to the current directory.
\nYou can use any directory name as the base directory for find to search<\/p>\n
\nDirectories and files) use.
\nfind . – print<\/p>\n
\nYou want the output to be similar to that of ls command, use find as follows.
\n \/home\/Varsha $ find – type f -ls
\n244269 33 -rw-r–r– 1 Varsha Trainee 60 Nov 9 23:58 .\/ebooks\/perl\/1.Strings\/chapter1
\n235915 86 -rw-r–r– 1 Varsha Trainee 215 Nov 9 11:26 .\/ebooks\/perl\/1.Strings\/chapter2
\n104841 25 -rw-r–r– 1 Varsha Trainee 554 Nov 9 11:26 .\/ebooks\/perl\/1.Strings\/chapter3
\n104838 32 -rw-r–r– 1 Varsha Trainee 510 Nov 9 11:26 .\/ebooks\/perl\/10.Subroutines\/chapter1
\n104840 33 -rw-r–r– 1 Varsha Trainee 55 Nov 9 11:26 .\/ebooks\/perl\/10.Subroutines\/chapter2
\n..
\n^C<\/p>\n
\nI-node number
\n Size in kilobytes (1024 bytes)
\n Protection mode
\n Number of hard links
\n User
\n Group
\n Size in bytes
\n Modification time <\/p>\n
\n Find also helps in retrieving the files which are a modified n days before or modified after n days. Where n is any integer.
\nSuppose you want the list of all the files which are modified 5 days ago so that it can be removed after archiving It.
\n\/home\/varsha $ date
\nFri Dec 23 21:16:06 IST 2011
\n\/home\/varsha $ find . \u2013type f -mtime +5 >file_list_5<\/p>\n
\nSimilarly you can use -5 instead of +5 for files modified after 5 days.<\/p>\n
\nto find all the find all the files which are greater or less than a particular size, use \u2013size option.<\/p>\n
\n\/home\/varsha $ find . \u2013size +100c<\/p>\n
\nTo find all files which are created after the modification time of a particular file,use find with -newer option.
\nIf you want to list all the files that were created after 2013-05-31 06:25 <\/p>\n
\n244269 33 -rw-r–r– 1 Varsha Trainee 0 May 31 06:25<\/p>\n
\n.\/BATCH
\n.\/BATCH\/arguments.bat
\n.\/BATCH\/arith.bat
\n.\/BATCH\/for_loop.bat
\n.\/BATCH\/if_condn.bat
\n.\/BATCH\/if_condn.bat.bak
\n.\/misc
\n.\/misc\/vim_list.txt
\n.\/PERL
\n.\/PERL\/a1.txt
\n.\/PERL\/a1.txt.orig
\n.\/PERL\/a2.txt
\n.\/PERL\/a2.txt.orig
\n.\/PERL\/all_dir.txt<\/p>\n
\nor just to print a newline character.<\/p>\n
\nIt can be used to print a string and a variable together.<\/p>\n
\nMy Home is \/home\/b4578
\n\/home\/b4578$<\/p>\n
\nie:-
\n\/home\/b4578$ echo \u201cmy \\$HOME variable is set to $HOME\u201d
\nmy \\$HOME variable is set to \/home\/b4578<\/p>\n
\nTo display double quote character \u201c use a backslash.
\nSuppose you want to display a html form tag. use echo as shown in a script.
\n#!\/usr\/bin\/sh
\n#……….lines of code
\necho \u201c\u201d
\necho \u201c
\necho \u201c<\/p>\n