In all shells apart from the Bourne shell you can use the alias command to create your own names or abbreviations for commands by performing string substitution on the command line according to your specifications. However the format of the alias command is shell dependant.
alias [ new [ old]] C Shell
alias -x new=old Korn Shell
alias new=old zsh Shell
When you enter new the shell substitutes
old. In the Korn Shell the -x option causes the alias to be
exported to child processes.
The following example causes ls -l to be executed when the command ll is entered:
alias ll ls -l - C Shell
alias -x ll='ls -l' - Korn Shell
The following example creates the command dir to list directory files only:
alias dir 'ls -l 
grep ^d' - C Shell
alias dir='ls -l | grep^d' - Korn Shell
grep in this case searches for a d in the first column of each
line of the output of the ls -l command.