我可以让PATH变量求值到我所在的目录吗？

Question

On linux using bash ,
lets say I made two programs both called print_report .
(They are in different directories.)

Inside my .bashrc file, I have:

PATH="path/to/print_report1/:$PATH"

This allows me to type print_report anywhere and it will run one of the programs.

---

How can I have bash decide to use one or the other depending on the working directory?

for example,
If I'm currently in ~/project1/ and type print_report it will use /bin/foo/print_report
If I'm currently in ~/project2/ and type print_report it will use /bin/bar/print_report

Answer 1

You can't do that as such. Instead, write a wrapper script or function that checks the current directory and invokes the right command:

#!/bin/bash
if [[ $PWD == $HOME/project1/* ]]
then
    /bin/foo/print_report "$@"
elif [[ $PWD == $HOME/project2/* ]] 
then
    /bin/bar/print_report "$@"
else
    echo "Don't know how to print_report for $PWD"
fi

Answer 2

This is a security disaster waiting to happen, (which is to say you really don't want to do this) but you can certainly do something like:

cd() {
    dir=${1-.}
    case $dir in)
        path1) PATH=/path/for/working/in/path1;;
        path2) PATH=/path/for/working/in/path2;;
        *) PATH=/bin:/usr/bin;;
    esac
    command cd $dir
}

(Put that in your .bashrc or just define it in the current shell.)

Answer 3

You can emulate preexec hooks à la zsh, using the DEBUG trap.

In that way, every time a command is executed, you can run a preexec hook to check $PWD, and adjust $PATH accordingly.

You can include a preexec hook doing what you want in your .bashrc.

Answer 4

Everything presented here so far strikes me as overly complicated and needlessly complex hackery. I would just place a Makefile in each directory with

report:
        /bin/foo/print_report

in ~/project1/Makefile , and

report:
        /bin/bar/print_report

in ~/project2/Makefile . This extends easily to as many directories and programs you want. And you only need to type make instead of those longwinded command names :-)