{"id":5496,"date":"2015-12-28T13:02:52","date_gmt":"2015-12-28T05:02:52","guid":{"rendered":"http:\/\/rmohan.com\/?p=5496"},"modified":"2015-12-28T17:42:19","modified_gmt":"2015-12-28T09:42:19","slug":"rhce7-certification-study-notes","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=5496","title":{"rendered":"RHCE7 certification study notes"},"content":{"rendered":"

RHCE7 certification study notes<\/strong><\/p>\n

— system file directory structure<\/p>\n

, RHEL7 system file directory<\/p>\n

Basically RHEL7 directory structure remains the same as the original directory structure RHEL6,
\nthe difference is, RHEL7 increasing the Run directory, the default file is used to automatically mount CD-ROM, and CD-ROM in RHEL6 default mount directory is the Media.<\/p>\n

choose manual zoning, you must divide the partition: \/, boot, swap.<\/p>\n

2, reinstall the system, you only need to format the “\/” directory to other directories on their own partitions without formatting, keeping the original user files are not deleted<\/p>\n

 <\/p>\n

[root@RHEL7HARDEN \/]# ls
\nbin\u00a0 boot\u00a0 dev\u00a0 etc\u00a0 home\u00a0 lib\u00a0 lib64\u00a0 media\u00a0 mnt\u00a0 opt\u00a0 proc\u00a0 root\u00a0 run\u00a0 sbin\u00a0 srv\u00a0 sys\u00a0 tmp\u00a0 usr\u00a0 var
\n[root@RHEL7HARDEN \/]#<\/p>\n

 
\nstudy notes 2<\/p>\n

— command line file<\/p>\n

1, create and delete files<\/p>\n

Create a file touch xxxx<\/p>\n

touch -t 20151225 create a file and specify time properties<\/p>\n

rm xxx\u00a0 delete the file<\/p>\n

rm -rf forced to delete files<\/p>\n

2. Create a directory and delete the directory<\/p>\n

mkdir -p xxx\/yyy recursively create directories;<\/p>\n

rmdir xxx delete empty directories;<\/p>\n

rm -rf XXX\u00a0 forcibly remove non-empty directories;<\/p>\n

3, copy files and directories<\/p>\n

cp \/path1\/xxx \/path2\/xxx\/<\/p>\n

cp -p \/path1\/xxx \/path2\/yyy copy files to retain the original file attributes;<\/p>\n

cp -Rf (or -rf)\/path1\/ \/path2\/ copy files to a directory directory path1 path2<\/p>\n

cp -a\u00a0\u00a0 cp -dR –preserve=all<\/p>\n

4 Cut files<\/p>\n

mv \/path1\/xx \/path2\/yy<\/p>\n

5 View Files<\/p>\n

cat xx less
\nmore
\nless<\/p>\n

3– redirection and piping<\/p>\n

Redirect correct content:<\/p>\n

cat xx.file> yy.file equivalent<\/p>\n

cat xx.file 1> yy.file redirected to the file contents yy.file, will overwrite the original file contents;<\/p>\n

cat \/etc\/passwd & >> \/tmp\/xx<\/p>\n

cat \/etc\/passwd > \/tmp\/xx 2>&1<\/p>\n

tail -f \/var\/log\/messages >\/tmp\/xx 2>\/tmp\/yy<\/p>\n

ps\u00a0 aux | grep tail | grep -v ‘grep’<\/p>\n

ls -al \/dev\/<\/p>\n

to redirect the file contents input to a command<\/p>\n

tr<\/p>\n

cat > \/tmp\/xxx <<EOF
\n>test1
\n>test2
\n>test3
\n>EOF<\/p>\n

cat <<EOF> \/tmp\/xxx
\n>test2
\n>test3
\n>test4
\n>EOF<\/p>\n

number of rows grep -n before looking for the number of rows plus -i ignore case, -A 3 looking for then displayed, B 3 show the number of rows -v looking for negative keywords before after content, -q Do not display output;<\/p>\n

grep -n1 B1 -A root \/etc\/passwd<\/p>\n

ifconfig | grep ‘inet’|grep -v ‘inet6’| awk ‘BEGIN{print “IP\\t\\tnetmask”}{print $2,”\\t”,$4}END{}’<\/p>\n

ifconfig | grep ‘inet’|grep -v ‘inet6’| tee -a \/tmp\/yy|awk ‘BEGIN{print “IP\\t\\tnetmask”}{print $2,”\\t”,$4}END{}’<\/p>\n

4 – Vim editor use<\/p>\n

1, gedit graphical editing files<\/p>\n

2, Vim operating a file, if the file exists is opened, if the file does not exist, it is created:<\/p>\n

When using Vim to edit the file to open, the default is the command-line mode:<\/p>\n

4. When you edit the file, enter the command line insert mode, press the following keys to enter:<\/p>\n

i, from the current cursor enters;<\/p>\n

a, from the current cursor one character to enter;<\/p>\n

o, in the current row into the next row;<\/p>\n

I, from the current cursor jump to the beginning of the line and into the Bank;<\/p>\n

A, skip to the end and enter the Bank;<\/p>\n

O, in the Bank of the line to insert a row;<\/p>\n

r, to replace the current character;<\/p>\n

R, to replace the current character and move to the next character;<\/p>\n

number + G: jump to a specific row, such as 10G jumps to line 10, GG jump to the last line, gg jump to the first line;<\/p>\n

number + yy: copy current number of rows down, in any line can be pasted by p;<\/p>\n

number + dd: Cut down the number of rows currently in any line adhesive according to p;<\/p>\n

u: undo the last step of the operation;<\/p>\n

ctrl + r: to restore the previous step;<\/p>\n

ctrl + v: to enter visual block mode, the cursor moves up and down, select the content, press y copy selected content, at any position by pasting;<\/p>\n

Fast beginning of the line to add a comment #, move the cursor to select the line, then press I to the start position,<\/p>\n

press #, press ESC to exit<\/p>\n

#abrt:x:173:173::\/etc\/abrt:\/sbin\/nologin
\n#pulse:x:171:171:PulseAudio System Daemon:\/var\/run\/pulse:\/sbin\/nologin
\n#gdm:x:42:42::\/var\/lib\/gdm:\/sbin\/nologin
\n#gnome-initial-setup:x:993:991::\/run\/gnome-initial-setup\/:\/sbin\/nologin
\n:split?ctrl+w<\/p>\n

To view detailed help Vim, you can enter Vimtutor.<\/p>\n

5, line mode to save the file, find, property settings, replacement and other operations<\/p>\n

Enter the last line mode, ESC from insert into command mode, enter \ud83d\ude41 \/ or generally used to find, n from the look down, N from the look-up)<\/p>\n

Save: wq to save and exit, or x;<\/p>\n

Force Quit: q without saving the file content;!<\/p>\n

Display line numbers: set nu, if the default display line numbers, you will need to modify the home directory vimrc file or \/ etc \/ vimrc, no file is created, insert a row set nu;<\/p>\n

Switching specified line: direct input line number;<\/p>\n

Replace: 1,$s \/old \/new \/g Replace globally all<\/p>\n

m, ns \/old \/new \/g replace m row to match the contents of all n rows, on behalf of the current line, $representatives last line,
\n$ -. 1 represents the penultimate line, (1, $) can also be used to replace%,
\nThey are expressed full text. If you want to match the contents of which have special characters such as \/, *, etc., to be added in front of the escape character \\<\/p>\n

You can use the s # old # new #, using the # separator, the special characters do not need to escape;<\/p>\n

Find backslash below, if you want to ignore the case, look at the back of the content plus \\ c, for example: \/ servername \\ c<\/p>\n

study notes 5– manage users and user groups<\/p>\n

[root@RHEL7HARDEN \/]# passwd –help
\nUsage: passwd [OPTION…] <accountName>
\n-k, –keep-tokens\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 keep non-expired authentication tokens
\n-d, –delete\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 delete the password for the named account (root only)
\n-l, –lock\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 lock the password for the named account (root only)
\n-u, –unlock\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 unlock the password for the named account (root only)
\n-e, –expire\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 expire the password for the named account (root only)
\n-f, –force\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 force operation
\n-x, –maximum=DAYS\u00a0\u00a0\u00a0\u00a0\u00a0 maximum password lifetime (root only)
\n-n, –minimum=DAYS\u00a0\u00a0\u00a0\u00a0\u00a0 minimum password lifetime (root only)
\n-w, –warning=DAYS\u00a0\u00a0\u00a0\u00a0\u00a0 number of days warning users receives before password expiration (root only)
\n-i, –inactive=DAYS\u00a0\u00a0\u00a0\u00a0 number of days after password expiration when an account becomes disabled (root only)
\n-S, –status\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 report password status on the named account (root only)
\n–stdin\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 read new tokens from stdin (root only)<\/p>\n

Help options:
\n-?, –help\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Show this help message
\n–usage\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Display brief usage message
\n[root@RHEL7HARDEN \/]#<\/p>\n

[root@RHEL7HARDEN \/]# chage –help
\nUsage: chage [options] LOGIN<\/p>\n

Options:
\n-d, –lastday LAST_DAY\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set date of last password change to LAST_DAY
\n-E, –expiredate EXPIRE_DATE\u00a0 set account expiration date to EXPIRE_DATE
\n-h, –help\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 display this help message and exit
\n-I, –inactive INACTIVE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set password inactive after expiration
\nto INACTIVE
\n-l, –list\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 show account aging information
\n-m, –mindays MIN_DAYS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set minimum number of days before password
\nchange to MIN_DAYS
\n-M, –maxdays MAX_DAYS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set maximim number of days before password
\nchange to MAX_DAYS
\n-R, –root CHROOT_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 directory to chroot into
\n-W, –warndays WARN_DAYS\u00a0\u00a0\u00a0\u00a0\u00a0 set expiration warning days to WARN_DAYS<\/p>\n

root@RHEL7HARDEN \/]# useradd –help
\nUsage: useradd [options] LOGIN
\nuseradd -D
\nuseradd -D [options]<\/p>\n

Options:
\n-b, –base-dir BASE_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 base directory for the home directory of the
\nnew account
\n-c, –comment COMMENT\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 GECOS field of the new account
\n-d, –home-dir HOME_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 home directory of the new account
\n-D, –defaults\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 print or change default useradd configuration
\n-e, –expiredate EXPIRE_DATE\u00a0 expiration date of the new account
\n-f, –inactive INACTIVE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 password inactivity period of the new account
\n-g, –gid GROUP\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 name or ID of the primary group of the new
\naccount
\n-G, –groups GROUPS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 list of supplementary groups of the new
\naccount
\n-h, –help\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 display this help message and exit
\n-k, –skel SKEL_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 use this alternative skeleton directory
\n-K, –key KEY=VALUE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 override \/etc\/login.defs defaults
\n-l, –no-log-init\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 do not add the user to the lastlog and
\nfaillog databases
\n-m, –create-home\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 create the user’s home directory
\n-M, –no-create-home\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 do not create the user’s home directory
\n-N, –no-user-group\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 do not create a group with the same name as
\nthe user
\n-o, –non-unique\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 allow to create users with duplicate
\n(non-unique) UID
\n-p, –password PASSWORD\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 encrypted password of the new account
\n-r, –system\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 create a system account
\n-R, –root CHROOT_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 directory to chroot into
\n-s, –shell SHELL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 login shell of the new account
\n-u, –uid UID\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 user ID of the new account
\n-U, –user-group\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 create a group with the same name as the user
\n-Z, –selinux-user SEUSER\u00a0\u00a0\u00a0\u00a0 use a specific SEUSER for the SELinux user mapping<\/p>\n

[root@RHEL7HARDEN \/]# usermod –help
\nUsage: usermod [options] LOGIN<\/p>\n

Options:
\n-c, –comment COMMENT\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new value of the GECOS field
\n-d, –home HOME_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new home directory for the user account
\n-e, –expiredate EXPIRE_DATE\u00a0 set account expiration date to EXPIRE_DATE
\n-f, –inactive INACTIVE\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set password inactive after expiration
\nto INACTIVE
\n-g, –gid GROUP\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 force use GROUP as new primary group
\n-G, –groups GROUPS\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new list of supplementary GROUPS
\n-a, –append\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 append the user to the supplemental GROUPS
\nmentioned by the -G option without removing
\nhim\/her from other groups
\n-h, –help\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 display this help message and exit
\n-l, –login NEW_LOGIN\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new value of the login name
\n-L, –lock\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 lock the user account
\n-m, –move-home\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 move contents of the home directory to the
\nnew location (use only with -d)
\n-o, –non-unique\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 allow using duplicate (non-unique) UID
\n-p, –password PASSWORD\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 use encrypted password for the new password
\n-R, –root CHROOT_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 directory to chroot into
\n-s, –shell SHELL\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new login shell for the user account
\n-u, –uid UID\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 new UID for the user account
\n-U, –unlock\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 unlock the user account
\n-Z, –selinux-user SEUSER\u00a0\u00a0\u00a0\u00a0 new SELinux user mapping for the user account<\/p>\n

[root@RHEL7HARDEN \/]# useradd test1
\n[root@RHEL7HARDEN \/]#\u00a0 mkdir \/home\/test
\nroot@RHEL7HARDEN \/]# usermod -d \/home\/test1 test
\nusermod: user ‘test’ does not exist
\n[root@RHEL7HARDEN \/]# cp -a \/etc\/skel\/.[^.]* \/home\/test\/
\n[root@RHEL7HARDEN \/]# groups test1
\ntest1 : test1
\nusermod -a -G mohan test1<\/p>\n

usermod -g<\/p>\n

[root@RHEL7HARDEN \/]# gpasswd –help
\nUsage: gpasswd [option] GROUP<\/p>\n

Options:
\n-a, –add USER\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 add USER to GROUP
\n-d, –delete USER\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 remove USER from GROUP
\n-h, –help\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 display this help message and exit
\n-Q, –root CHROOT_DIR\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 directory to chroot into
\n-r, –delete-password\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 remove the GROUP’s password
\n-R, –restrict\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 restrict access to GROUP to its members
\n-M, –members USER,…\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 set the list of members of GROUP
\n-A, –administrators ADMIN,…
\nset the list of administrators for GROUP
\nExcept for the -A and -M options, the options cannot be combined.<\/p>\n","protected":false},"excerpt":{"rendered":"

RHCE7 certification study notes<\/p>\n

— system file directory structure<\/p>\n

, RHEL7 system file directory<\/p>\n

Basically RHEL7 directory structure remains the same as the original directory structure RHEL6, the difference is, RHEL7 increasing the Run directory, the default file is used to automatically mount CD-ROM, and CD-ROM in RHEL6 default mount directory is the Media.<\/p>\n

choose […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[73],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/5496"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5496"}],"version-history":[{"count":3,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/5496\/revisions"}],"predecessor-version":[{"id":5501,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/5496\/revisions\/5501"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5496"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5496"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5496"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}