How can I force the use of a specific binary when running a script

Question

How can I force a specific binary to be used when executing a bash script?

I have a bash script which uses the "php" binary.

There are several php versions on my computer. The main php binary, as configured via the PATH variable, is not the one to be used in this case.

Normally the script will be executed like this:

./script.sh

I need something like this:

php=/usr/bin/php ./script.sh

NOTE: It is not an option to temporary change the PATH variable just for this command, because this will affect other dependencies.

Hardcoding it in the script is also not an option, because the script is used by multiple people. So when other people execute the script it should just use the main php binary as specified in the PATH variable.

I don't want it to be accessible via a variable. I actually want to specify the exact location to look for the binary. Just like it would normally do by using PATH, only now for one single binary with the absolute path to it. If this script calls another script, that second script also needs to use that php version. –

Answer 1

This would work:

php() {  /path/to/your/php $@; }; export -f php; ./script.sh ; unset -f php

To break it down:

php() {  /path/to/your/php $@; }; 

Defines a shell function that will pass all of its arguments to the php path you provide.

export -f php

Exports the newly created function for use within your script

./script.sh

Executes your script

unset -f php

Removes the shell function we defined earlier.

Answer 2

One way to do it would be to add an additional variable to your script:

PHP=$1
if [ -z $PHP ]; then
    PHP=php
fi

Then, if you run it without specifing anything, it will use the default PHP binary. Else, it will use the one you'll pass through your variable

./script.sh /usr/bin/php

Answer 3

$ hash /usr/local/bin php
$ php file.php

help :

$ LANG=C help hash
hash: hash [-lr] [-p pathname] [-dt] [name ...]
    Remember or display program locations.

    Determine and remember the full pathname of each command NAME.  If
    no arguments are given, information about remembered commands is displayed.

    Options:
      -d                forget the remembered location of each NAME
      -l                display in a format that may be reused as input
      -p pathname       use PATHNAME is the full pathname of NAME
      -r                forget all remembered locations
      -t                print the remembered location of each NAME, preceding
                each location with the corresponding NAME if multiple
                NAMEs are given
    Arguments:
      NAME              Each NAME is searched for in $PATH and added to the list
                of remembered commands.

    Exit Status:
    Returns success unless NAME is not found or an invalid option is given.

Answer 4

You say NOTE: It is not an option to temporary change the PATH variable just for this command, because this will affect other dependencies, but I think it is an option if you do it right.

You can create a personal directory that has only your desired php in it, and put that personal directory first in your own PATH. That personal PATH entry will affect the shell finding only that one php binary, and not affect any other PATH dependencies. Other people running the script won't use your PATH, so it won't affect them. For example:

$ mkdir -p "$HOME/myphp"
$ ln -s /usr/bin/php "$HOME/myphp/"
$ PATH=$HOME/myphp:$PATH
$ ./script.sh

The above method only affects the one php program, nothing else, and it only affects it for you, not anyone else.

Of course you can put your new PATH definition in the shell start-up file for your account so that only the commands you run will use this version of php.