Go4Expert - Shell Tips & Tricks

Shell Tips & Tricks

Create A Command Alias

Most of us use 'ls -l' so, will it not be easier to have a smaller command to show us long listing, add the following line to ~/.bashrc

Code:

alias ll='ls -l'

Using it

Code:

[root@pradeep ~]# ll

total 264

-rw------- 1 root   root     1221 May 21 21:57 anaconda-ks.cfg

-rw-r--r-- 1 root   root     2063 Jul 20 12:21 content_passlimit.txt

drwxr-xr-x 2 root   root     4096 Jul 20 16:09 dumps

-rw-r--r-- 1 root   root    35779 May 21 21:56 install.log

-rw-r--r-- 1 root   root     5142 May 21 21:56 install.log.syslog

drwxr-xr-x 7 root   root     4096 Jun 24 16:23 json-1.2.0

-rw-r--r-- 1 root   root    13286 Mar 15  2006 json-1.2.0.tgz

-rw-r--r-- 1 root   root       17 Aug 10 13:30 lwp_cookies.dat

-rw------- 1 root   root   141066 May 29 17:47 mbox

-rw-r--r-- 1 root   root    11484 Jul  6 13:01 modify_printfile.pl

-rw-rw-r-- 1 nagios nagios   4289 Mar 15  2006 package.xml

drwxr-xr-x 2 root   root     4096 Jul 27 19:29 test

drwxr-xr-x 2 root   root     4096 Jul 18 12:19 test1

You may create as many aliases as you want. Please share any interesting aliases you create.

Use Previous Command's Arguments

Running a command with the same arguments used in the previous command, use '!*' to repeat all arguments or '!:2' to use the second argument. '!$' uses the last argument. Let's see a few examples.

Code:

[root@pradeep ~]# mkdir -p /tmp/pradeep/test/shell

[root@pradeep ~]# cd !$

cd /tmp/pradeep/test/shell

[root@pradeep shell]# mkdir -p /tmp/pradeep/test2 /tmp/pradeep/test3

[root@pradeep shell]# chmod -R 777 !:2 !:3

chmod -R 777 /tmp/pradeep/test2 /tmp/pradeep/test3

[root@pradeep shell]# touch a.txt b.txt

[root@pradeep shell]# ls !*

ls a.txt b.txt

a.txt  b.txt

[root@pradeep shell]# ls -l !*

ls -l a.txt b.txt

-rw-r--r-- 1 root root 0 Aug 10 13:54 a.txt

-rw-r--r-- 1 root root 0 Aug 10 13:54 b.txt

[root@pradeep shell]#

Useful Bash Keystrokes

Ctrl+U - Cuts everything to the left
Ctrl+W - Cuts the word to the left
Ctrl+Y - Pastes what's in the buffer
Ctrl+A - Go to beginning of line
Ctrl+E - Go to end of line
Ctrl+R - Search command history

Changing File Extensions

Code:

rename 's/.html$/.html.bak/' *.html

This will change all .html files to html.bak

Run a second command only if the first one is successfull

Code:

cd /tmp/pradeep/test/shell && tar xjvf /home/pradeep/songs.tar.bz

This is usually used like this 'make && make install' while compiling softwares.