[SOLVED] How to modify a variable command in bash without redefining it?

Issue

Say I have a variable command $EXPORT that is defined as something like

EXPORT=$(eval "export PYTHONPATH=/path/to/package1:$PYTHONPATH")

However, I want the command to export a new package2 instead of package1 to $PYTHONPATH. Note that I want to do it by modifying the current $EXPORT variable instead of redefining it. What I have tried is to replace the string "/path/to/package1" by "/path/to/package2":

echo ${$EXPORT//"/path/to/package1"/"/path/to/package2"}

but I am getting "bad substitution" error.

So what is the proper way to modify a variable command in bash?

Solution

Don't store code in variables, Variables are for storing data, functions are for storing code. See https://mywiki.wooledge.org/BashFAQ/050.

I think you might want this (untested):

do_export() { export PYTHONPATH="${1:-/path/to/package1}:$PYTHONPATH"; }

mycmd() { ls "${1:-./}"; )

which you'd then run as do_export '/path/to/package2' to prepend package2 instead of package1 to PYTHONPATH and mycmd .. to run ls on the parent dir for example.

Answered By - Ed Morton

Answer Checked By - Pedro (WPSolving Volunteer)