Linux Commands

uname –help
uname -r
grep model /proc/cpuinfo
grep MemFree /proc/meminfo
sudo -u root lastcomm -f /var/account/pacct
cat /proc/version
# cat /proc/cpuinfo
# cat /proc/meminfo
# cat /proc/zoneinfo
# cat /proc/mounts
cat /etc/redhat-release
grep MemTotal /proc/meminfo
grep SwapTotal /proc/meminfo
df -k /tmp
grep “model name” /proc/cpuinfo
ifconfig (/sbin/ifconfig)
uaname -r
lshal:detected hardware
rpm -qa:  display pakage
rpm -qa | less
Linux Kernel Information:

cat /etc/sysctl.conf
cat /etc/hosts
/sbin/ifconfig
Uname -r
cat /etc/security/limits.conf
cat /proc/sys/kernel/sem
cat /proc/sys/kernel/shmmax
cat /proc/sys/kernel/shmall
cat /proc/sys/kernel/shmmni
cat /proc/sys/fs/file-max
cat /proc/sys/net/ipv4/ip_local_port_range
/sbin/lsmod
cat /etc/issue
sysctl -a | grep shm
sysctl -a | grep ip_local_port_range
/etc/inittab:  init process determines which runlevel it should be
w, ps -a, ps -Alf, ps -AlFH, ps -AlLm
ps -u oracle, ps -u anguyen

top ? t, m, A: top consumer, r: renice, o: interactively select
vmstat 3, vmstat -m:memority slab info, vmstat -a
w, ps -a, ps -Alf, ps -AlFH, ps -AlLm
ps -u oracle, ps -u attunity
uptime
free
fee -s 2
watch -n 3 -d free
watch -d cat /proc/meminfo
sar -B -f /var/log/sa/sa14
sar -W -f /var/log/sa/sa14
vmstat -m
vmstat -a
ipcs -sm
ipcs -lms
sar -n DEV | more
sar 4 5
mpstat -P ALL
MEMORY intensive process:

ps -e -o pmem,pid,user,tty,args | grep -i oracle | sort -n -k 1 -r | head
watch -n 3 -d free
watch -d cat /proc/meminfo
CPU intensive process

top
ps -e -o pcpu,pid,user,tty,args | sort -n -k 1 -r | head
mpstat -P 0 2 20 (processor 0
mpstat -P ALL
sar -u -fDisk Storage
************************************
iostat -d 3, iostat 2 15
iostat -xd 10sorting files by size
***********************
ls -alS | head -5
mpstat -P ALL
sar 4 5
****************************************************
Network
**************************************************
lsmod | grep -i bonding
cat /etc/sysconfig/network-scripts/ifcfg-eth0 (check bonding)..the difference NETWORK, IPADDRESS, NETMASK
netstat -s | less
netstat –interfaces eth0
netstat -ptc
sar -n DEV
netstat -nat | awk ‘{ print $5}’ | cut -d: -f1 | sed -e ‘/^$/d’ | uniq
tcpdump -n -i eth1 -s 0 -w output.txt src or dst port 80
iptraf – Real-time Network Statistics
Network traffic
netstat -ptc
sar -n DEV
sar – Collect and Report System Activity
*************************************************
Oracle
***************************************************
cpio -idmv < 10201_database_linux_x86_64.cpio
id oracle
id nobody
pgrep sshd
env | grep PATH

detected hardware lshal:
init process determines which runlevel it should be /etc/inittab

shutdown
shutdown -t3 -r now
mount /dev/hda4 /data/oracle/bkup1:
grep ‘Ashley Nguyen’ /etc/passwd
find / -name install.log
sed ‘s/anguyen/lvu/’ /etc/passwd > /tmp/test
ps aux | grep nfs
free:
Ifconfig -a

To determine the amount of shared memory available, enter the following command:automatic memory management
# df -k /dev/shm/
To determine the distribution and version of Linux installed, enter the following command:
# cat /proc/version
To determine whether the required packages are installed, enter commands similar to the following:
# rpm -q package_name
Add group
# /usr/sbin/groupadd oper
Modify user:  usermod -g oinstall -G dba oracle
Create disks:
fdisk -l

give password to oracle user
passwd oracle

change ownership in linux
chown

clear screen
clear
TAR – backup / restore
tar -cf myfiles.tar *.trc (create)
tar xvf myfiles.tar (extract)

To create new directory

To copy an entire folder (directory tree) in Linux

For checking the size of current folder

To find the size of the hdd

To find out the size of the folder in the folder

See all files and their size

To output the number of files in the current directory

See all the jobs

To find out RAM size on Linux machine

Rename folder/filename

To find which process is consuming how much RAM?

To see the free ram memory

To update yum using corn

Create tar.gz file

Untar a tar file
tar czvf myfolder.tar.gz abcfolder/
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Delete bash History
Try to delete the content of ~/.bash_history

To add new user
* Adding a new user (useradd)
* Modifying an existing user (usermod)

Options:
* -d home directory
* -s starting program (shell)
* -p password
* -g (primary group assigned to the users)
* -G (Other groups the user belongs to)
* -m (Create the user’s home directory

User’s home directory should be 700. If you are operating a ~username type server, the public_html directory should be 777. You may also need to open up the home directory to 755.

For allowing sudo

To delete user

To display your crontab file

root can view any users crontab file by adding “-u username”

crontab -u bappy -l  # List bappy's crontab file.

tar tvf myfiles.tar (show the details)