I may or may not have the executable thing in my $PATH.
How can I neatly check this in a ZSH script?
I just run the command, sending the output and errors or noman's land, then check the result code.
thing > /dev/null 2>&1
thing_installed=$?
if [ $thing_installed -eq 0 ]; then
echo 'Thing Installed!'
fi
I feel like this could be done more neatly (one liner?).
In zsh, which behaves reasonably, so you can simply do
if which thing > /dev/null 2>&1; then
echo installed
fi
or
which thing > dev/null 2>&1 && echo installed
Note that which is a shell builtin, and its behavior is not reasonable in all shells, so this behavior cannot be relied upon.
thing was in your path.
test -e ls to answer the question 'is ls installed on my machine?'
-4 and counting!)For zsh whence is the tool you are looking for. With parameter -p it can be forced to look only in $PATH and ignore functions, builtins and aliases with the same name.
This will either return the path to thing or an error message:
whence -cp thing
use which thing and check result code
You can check whether the file exists by this expresion:
[ -e thing ] && echo 'Thing Installed!'
The -e operator checks whether the file exists or not. If you want to do other file tests take a look to this page: http://tldp.org/LDP/abs/html/fto.html.
Hope this was helpful ;-)
[ -e thing] does neither check executabilty nor does it look in $PATH. For this to find anyhing thing has to be in the current directory and even then it may be a directory instead of an executable file.
-x file True if file exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indicates that file can be searched.-4!-4when I accepted it... Glad you got some amusement out of it though ;)