bash alias help

Shell Programming and Scripting
1

I try the following alias:
alias psx='ps auxw | grep $1 | grep -v grep'
but it fails with "grep: yyy: No such file or directory" (for 'psx yyy' command).

the following is ok:
alias psx='ps auxw | grep $1'

why this happens?
how to overcome this?

thanks

2

An alias cannot have an argument like $1. You want to use a function instead.

psx () {
  ps auxw | grep "$1" | grep -v grep
}

Your second alias works by coincidence when $1 is empty in the current shell (as it will often be in an interactive bash); it expands to ps auxw | grep (empty string) yyy -- and ironically, if you had double-quoted $1 properly, it would also not have worked.

Your first alias expands to ps auxw | grep (empty string) | grep -v grep yyy

Search these forums for ways to avoid the grep -v grep elegantly; solutions have been posted a number of times.

3

You might it helpful to investigate the pgrep command if it is available on your system (I think it is on Solaris and Linux).

4

thanks!

Apparently many make this mistake, I found more than once $1's for aliases in .bashrc files...