if-then-else inside Bash Alias

Question

I am trying to make an alias for mv so it does its normal behaviour in normal folders and is replaced by git mv inside git repositories. I tried many ways. The if statement works, only the command git mv will not run correctly.

alias mv='"$(
if [ x`git rev-parse --show-toplevel 2> /dev/null` = x ]; 
    echo mv;  
else 
    echo "git mv"; 
fi)"'

Solution 1

I would use a function for that, like so:

gitmv()
{
    # If in a git repo - call git mv. otherwise- call mv
    if [ x`git rev-parse --show-toplevel 2> /dev/null` = x ]; 
    then
        mv "$@"  
    else 
        git mv "$@" 
    fi
}

Edit:

alias mv=gitmv

Solution 2

Although jhscheer proposed a much better solution (IMHO), it is still possible to achieve what you were trying to do with only an alias.

Your alias did not work because of the external double quotes, which make git mv a single token, and you have no git mv executable. If you remove the external double quotes, your alias should work fine.

By the way, the inner double quotes, in echo "git mv" are useless, but harmless.

I have no git repository immediately available to test, but I just tried with the following alias:

alias foo='$(if [ x"`pwd`" = x"$HOME" ] ; then echo echo; else echo echo foo; fi)'

Comments

[Admin]

... Or even a little custom script

[Admin]

Regarding the contents of your alias, there's no reason to use git mv instead of mv because git will detect moves based on content. Rather move and commit, without changing the file, and AFTER commit modify the file. That way git will know that the file is moved.

[Admin]

@Highmastdon true, but the alias has the advantage of making the task faster, easier and cleaner. faster: not having to look am I inside or outside the repo, use only 1 command in git. easier: only the simple mv command everywhere, always. cleaner: no unwanted commit messages floating around in the git history that have to get cleaned out before committing to the company git that has strict rules on commit messages and kind of work that is allowed to have a separate commit. your solution would add commands even if you dont clean up the commits afterwards.

[jhscheer]

"There is no mechanism for using arguments in the replacement text. If arguments are needed, a shell function should be used." gnu.org/software/bash/manual/html_node/Aliases.html#Aliases

[switch87]

indeed, like Sato Katsura also recomanded me I already did it that way. I will edit your answer with my solution (almost the same but with alias)

[jhscheer]

@switch87: I'm glad you found a suitable solution for you. It seems your edit got rejected due to a conflict with another (random) edit. I'll add your alias.

[switch87]

Thank you for explaining why my first try did not work.