msoucy.me

Awesome WM startup fix

I was browsing the Awesome WM wiki to try to figure out how to autostart some commands on startup. The code at the end of the “Simple way” section seemed simple, but for some reason refused to work. I tried everything I could think of, blaming the pgrep command, but nothing seemed to work. Finally, I got frustrated, and forced Awesome to print out the entire command that was being run, then tried shoving that into my terminal.

It failed.

Wat.

Syntax error on |.

Then it hit me.

There are many shells that one can use. Some of them, like FISH, aren’t quite sh-compatible. Among the features that FISH has, it changes foo || bar into foo; or bar, which is slightly more verbose but cleaner to read (sometimes). The base command uses ||.

How do you fix this?

Luckily, sh has a special flag - -c. Calling sh -c 'foo' will pass foo to sh, so that sh parses it instead of whatever shell you’re using. This means that I can wrap the entire command in -c arguments, and it will work fine:

function run_once(prg,arg_string,pname,screen)
    if not prg then
        do return nil end
    end

    if not pname then
       pname = prg
    end

    if not arg_string then
        awful.util.spawn_with_shell("sh -c 'pgrep -f -u $USER -x \\'" .. pname .. "\\' || (" .. prg .. ")'",screen)
    else
        awful.util.spawn_with_shell("sh -c 'pgrep -f -u $USER -x \\'" .. pname .. " ".. arg_string .."\\' || (" .. prg .. " " .. arg_string .. ")'",screen)
    end
end