Why aliases in a non-interactive Bash shell do not work

Question

I am trying to use aliases in a non-interactive bash shell. I have defined my aliases in ~/.bashrc and I have set the variable BASH_ENV=~/startUpFile. The contents of the startUpFile are source ~/.bashrc.

I can see that my aliases are recognized, when I execute the alias command. However, if I try to use an alias defined in ~/.bashrc, Bash can't recognized it. It gives me the unknown command error.

With the TCSH shell it is pretty easy to do this because the ~/.cshrc file is always read.

Any ideas how I can do this with a Bash shell?

Answer 1

The command shopt -s expand_aliases will allow alias expansion in non-interactive shells.

Answer 2

.bashrc is only processed by interactive shells.

In addition, aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt. Unless, of course, POSIX mode is invoked by calling the shell with the name sh instead of bash.

People who use aliases a lot often source their .bashrc at the end of their profile so that the aliases are there even for non-interactive shells. This might not be the best way, but it is pretty common.

It's things like this that lead me to believe that in the 21st century we should abandon shell scripts in favor of a full-blown language like Python. It's a lot more predictable.

Answer 3

You have to

shopt -s expand_aliases

in the file pointed to in your BASH_ENV

Answer 4

I had similar issue, in the end, I found out that ~/.bashrc was all I needed.

However, in Ubuntu, I had to comment the line that stops processing ~/.bashrc :

If not running interactively, don't do anything
[ -z "$PS1" ] && return