Create and use aliases

• An alias is nothing but shortcut to commands.
• Use alias command to display list of all defined aliases.
• Add user defined aliases to ~/.bashrc file.

Create and use aliases

Use the following syntax:

alias name='command'
alias name='command arg1 arg2'

Examples

Create an aliase called c to clear the terminal screen, enter:

alias c='clear'

To clear the terminal, enter:

c

Create an aliase called d to display the system date and time, enter:

alias d='date'
d

Sample outputs:

Tue Oct 20 01:38:59 IST 2009

How do I remove the alias?

• Aliases are created and listed with the alias command, and removed with the unalias command. The syntax is:

unalias alias-name
unalias c 
unalias c d

To list currently defined aliases, enter:

alias

alias c='clear'
alias d='date'

If you need to unalise a command called d, enter:

unalias d
alias

If the -a option is given, then remove all alias definitions, enter:

unalias -a
alias

How do I permanently add aliases to my session?

• If you want to add aliases for every user, place them either in /etc/bashrc or /etc/profile.d/useralias.sh file. Please note that you need to create /etc/profile.d/useralias.sh file.
• User specific alias must be placed in ~/.bashrc ($HOME/.bashrc) file.

Sample ~/.bashrc file

• Example ~/.bashrc script:

# make sure bc start with standard math library
alias bc='bc -l'
# protect cp, mv, rm command with confirmation
alias cp='cp -i'
alias mv='mv -i'
alias rm='rm -i'
 
# Make sure dnstop only shows eth1 stats
alias dnstop='dnstop -l 5  eth1'
 
# Make grep pretty 
alias grep='grep --color'
 
# ls command shortcuts 
alias l.='ls -d .* --color=tty'
alias ll='ls -l --color=tty'
alias ls='ls --color=tty'
 
# Centos/RHEL server update 
alias update='yum update'
alias updatey='yum -y update'
# vi is vim 
alias vi='vim'
 
# Make sure vnstat use eth1 by default 
alias vnstat='vnstat -i eth1'

How do I ignore an alias?

Consider the following example:

alias ls='ls --color'

To ignore an alias called ls and run ls command, enter:

\ls

OR

"ls"

Or just use the full path:

/bin/ls
$(which ls)