Friday, December 30, 2011

Linux Quick Reference

-----------------------------------File Commands

ls                             – directory listing
ls -al                       – formatted listing with hidden files
cd dir                     - change directory to dir
cd                          – change to home
pwd                       – show current directory
mkdir dir              – create a directory dir
rm file                  – delete file
rm -r dir               – delete directory dir
rm -f file              – force remove file
rm -rf dir              – force remove directory dir *
cp file1 file2         – copy file1 to file2
cp -r dir1 dir2        – copy dir1 to dir2; create dir2 if it doesn't exist
mv file1 file2        – rename or move file1 to file2 if file2 is an existing directory, moves  file1  into Directory file2
ln -s file link          – create symbolic link link to file
touch file               – create or update file
cat > file               – places standard input into file
more file               – output the contents of file
head file               – output the first 10 lines of file
tail file                 – output the last 10 lines of file
tail -f file              – output the contents of file as it grows, starting with the last 10 lines
find size=0, mtime +2

-----------------------------------Process Management

ps                      – display your currently active processes
top                    – display all running processes
kill pid             – kill process id pid
killall proc       – kill all processes named proc *
bg                    – lists stopped or background jobs; resume a stopped job in the background
fg                    – brings the most recent job to foreground
fg n                 – brings job n to the foreground
vmstat
sar
iostat

-----------------------------------File Permissions

chmod octal file – change the permissions of file  to octal, which can be found separately for user,group, and world by adding:

? 4 – read (r)
? 2 – write (w)
? 1 – execute (x)

Examples:

chmod 777            – read, write, execute for all
chmod 755           – rwx for owner, rx for group and world

-----------------------------------SSH

ssh user@host                – connect to host as user
ssh -p port user@host    – connect to host on port
port as user
ssh-copy-id user@host    – add your key to host for
user to enable a keyed or passwordless login
scp  filename 10.150.1.26://home/app/.
ssh 10.150.1.26
ssh 10.150.1.26 date
-----------------------------------Searching

grep pattern files              – search for pattern in files
grep -r pattern dir             – search recursively for pattern in dir
command | grep pattern   – search for pattern in the output of command
locate file                         – find all instances of file

-----------------------------------System Info

date                        – show the current date and time
cal                         – show this month's calendar
uptime                  – show current uptime
w                          – display who is online
whoami                – who you are logged in as
finger user            – display information about user
uname -a               – show kernel information
cat /proc/cpuinfo    – cpu information
cat /proc/meminfo    – memory information
cat /etc/hosts
cat /etc/init.d/
cat /etc/var/log/messages
service network restart
cat /etc/sysctl.conf
/sbin/sysctl -p
man command        – show the manual for command
df                           – show disk usage
du                         – show directory space usage
free                       – show memory and swap usage
whereis app          – show possible locations of app
which app             – show which app will be run by default
fdisk -l
fdisk  /dev/sda
parted
umount /u01
mount -a
xhost +
vi .bash_profile
. .bash_profile
mounted
mounted.ocfs2 -d
mounted.ocfs2 -f
swap on
swap off
mkswap
groupadd oinstall
useradd oracle -g oinstall -G dba
passwd
mount -cifs 10.150.250.14://sharedfolder  /u01 -o user=root
fsck
unset
export
uname -a

-----------------------------------Compression

tar cf file.tar files                – create a tar named file.tar containing files
tar xf file.tar                        – extract the files from file.tar
tar czf file.tar.gz files          – create a tar with Gzip compression
tar xzf file.tar.gz                – extract a tar using Gzip
tar cjf file.tar.bz2               – create a tar with Bzip2 compression
tar xjf file.tar.bz2                – extract a tar using Bzip2
gzip file                             – compresses file and renames it to file.gz
gzip -d file.gz                   – decompresses file.gz back to file

-----------------------------------Installation

Install from source:
./configure
make
make install
dpkg -i pkg.deb – install a package (Debian)
rpm -Uvh pkg.rpm – install a package (RPM)
rpm -ivh pkg.rpm
rpm -qa pkg*

crontab -e

*  *  *  *  *  sh /u01/abc.sh
1  2  3  4  5

1  minutes
2  hours
3  days
4  months
5  weeks



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