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Aliasing a command and using it in the same line of code – Plesk

I was wondering if you could alias a command, and use it in the same line of code, see this example:

alias php=/opt/plesk/php/5.6/bin/php; php -v;

I want this to output PHP 5.6.

alias php=/opt/plesk/php/7.3/bin/php; php -v;

and I want this to output PHP 7.3. However, what I get is this:

php -v
# outputs 5.6

alias php=/opt/plesk/php/5.6/bin/php; php -v;
# outputs 5.6

alias php=/opt/plesk/php/7.3/bin/php; php -v;
# outputs 5.6

php -v
# outputs 7.3

I’ve tried the && operator but it has the same outcome.

I’m wanting to use this in a gitlab continuous integration script, which executes a script through ssh -t by passing a string. However I am calling several php functions and I dont want to paste the full php path every time:

ssh -v -tt $SSH_HOST_NAME "__my_php_commands_here__"

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3

Answers


  1. Chosen as BEST ANSWER
    0

    I've went with a .bashrc solution. I initially started with this but for some reason the aliases werent being picked up. It appears you need to set a custom expand_aliases setting.

    My .bashrc ended up looking like this:

    shopt -s expand_aliases;

alias php=/opt/plesk/php/7.3/bin/php;
alias composer=/usr/lib64/plesk-9.0/composer.phar;

    This seemed to do the trick and gave me the correct PHP version while using ssh [email protected] "php -v".


  2. 0

    I think the command line is being parsed, and aliases applied, before anything is executed. However, you can do it with shell functions. I don’t have PHP, but I have several Perl versions to test with:

    $ perl -v |grep version                      #  V
This is perl 5, version 26, subversion 2 (v5.26.2) built for x86_64-cygwin-threads-multi

$ perl(){ /usr/bin/perl "$@" ; } ; perl -v |grep version
This is perl 5, version 26, subversion 3 (v5.26.3) built for x86_64-cygwin-threads-multi
                                             #  ^

    So defining the pass-through function

    perl(){ /usr/bin/perl "$@" ; }

    changes how the word perl is interpreted later in the command line. Note that you do need the ; before } — see this answer.

    For your use case, I would recommend using a different name to avoid confusion. E.g.:

    currphp(){ /opt/plesk/php/5.6/bin/php "$@" ; } ; currphp -v
currphp(){ /opt/plesk/php/7.3/bin/php "$@" ; } ; currphp -v
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  3. 0

    in a gitlab continuous integration script

    Batch non-interactive shells don’t support aliases (by default). And that’s a good think. alias should be just used as your own, custom shorthand, not in batch scrips.

    You could

    a) define a function with the same name and use full path for command resolution:

    php() { /opt/plesk/php/5.6/bin/php "$@"; }
php -v

    Downsides: function are not exported, unless you add export -f php, it is a shell function. Something like xargs php will work incorrectly.

    b) use a varaible.

    php=/opt/plesk/php/5.6/bin/php
"$php" -v

    Downside: you have to modify all scripts and always check out for the $php.

    c) Modify the path, so your php is found first. You could create a temporary directory and add it to path:

    tmpd=$(mktemp -d)
trap 'rm -r "$tmpd"' EXIT
ln -s /opt/plesk/php/5.6/bin/php "$tmpd"/php
export PATH="$tmpd"/php:$PATH
php -v

    If you export PATH correctly, it will work everywhere. Remember to remove the folder tho.

    Side note: You don’t “alias a variable”, you “alias a command”. alias allows you to substitute the first (and only the first) word in a simple command. php is a command.

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