Where is what

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	venam Offline \| 05-06-2017, 11:19 AM \| #1

Hello fellow nixers,
This thread is about this:

Code:
~ > which which

which: shell built-in command

 ~ > type -a which  

which is a shell builtin

which is /usr/bin/which

 ~ > type -a type

type is a shell builtin

 ~ > type -a whereis

whereis is /usr/bin/whereis

 ~ > which cat

/usr/bin/cat

 ~ > type -a cat

cat is /usr/bin/cat

 ~ > whereis cat

cat: /usr/bin/cat /usr/share/man/man1/cat.1.gz /usr/share/man/man1/cat.1p.gz

Let's list all possible ways to find out where a program is, be it built in or not, POSIX or not.

	evbo Offline \| 05-06-2017, 12:20 PM \| #2

I don't know if this is weird or not, but I usually forget about which and do the following:

Code:
$ find / -name "which"

/bin/which

And for fun, here's an example of how to not optimize a search:

Code:
#!/usr/bin/env python3

import os

import re

import sys

def find_file(root, path):

    regex = re.compile(r"^" + re.escape(path) + r"$")

    for root, dirs, files in os.walk(root):

        for file in files:

            if regex.search(file):

                print(os.path.join(root,file))

find_file('/', str(sys.argv[1]))

	xero Offline \| 05-06-2017, 12:58 PM \| #3

* note i'm truncating the output of these commands as an example *

the posix way is to use "command":

Code:
[~]── - command -v 2bwm

/usr/local/bin/2bwm

there's also "whereis":

Code:
[~]── - whereis 2bwm

2bwm: /usr/local/bin/2bwm

the "locate" command finds files by name:

Code:
[~]── - locate 2bwm

/home/xero/dotfiles/2bwm

/home/xero/src/2bwm/2bwm.c

/usr/local/man/man1/2bwm.1

/usr/local/share/man/man1/2bwm.1

but "which" is my favorite:

Code:
[~]── - which 2bwm

/usr/local/bin/2bwm

you can use the "find" utility with the name flag:

Code:
[~]── - find -name 2bwm

./dotfiles/2bwm

./src/2bwm

./src/2bwm/2bwm

you also have other tools you can install to aid in your searching.

"ag", the silver searcher, can search file contents (default) or file and location names with the -g flag

Code:
[~]── - ag -g 2bwm

dotfiles/2bwm/bin/wm

src/2bwm/2bwm.c

src/2bwm/tags

src/2bwm/Makefile

you can get the same results with ack, but it's much slower.

Code:
[~]── - ack -g 2bwm

dotfiles/2bwm/bin/wm

src/2bwm/2bwm.c

src/2bwm/tags

src/2bwm/Makefile

you can also search the inverse way looking for binaries by man page topics using "apropos":

Code:
[~]── - apropos "window manager"

2bwm (1)             - A small and fast keyboard driven window manager with two borders.

package managers can also give you some good info:

on arch "pacman" can display a file install location list based on package name:

Code:
[~]── - pacman -Ql php

php /etc/

php /etc/php/

php /etc/php/conf.d/

php /etc/php/php.ini

php /usr/

php /usr/bin/

php /usr/bin/phar

php /usr/bin/phar.phar

php /usr/bin/php

php /usr/share/man/man1/phar.1.gz

php /usr/share/man/man1/phar.phar.1.gz

php /usr/share/man/man1/php-config.1.gz

php /usr/share/man/man1/php.1.gz

if you use an "rpm" based distribution (centOS, rhel, SUSE, opensuse, etc):

Code:
[~]── - rpm -ql findutils

/bin/find

/usr/bin/find

/usr/bin/xargs

if you use a "dpkg" based dist (debian, ubuntu and it's derivatives):

Code:
[~]── - dpkg --status some_package

[~]── - dpkg --listfiles some_package

[~]── - dpkg --search some_file

	alxndr Offline \| 05-06-2017, 03:13 PM \| #4

Code:
tree -f | grep '/firefox$'

	yossarian Offline \| 05-06-2017, 10:02 PM \| #5

I usually use bash's (POSIX) "command" built-in, since it catches aliases and functions in addition to normal utilities on the PATH:

Code:
$ command -v ls

/bin/ls

$ command -v gs

alias gs='git show'

I usually add a function like this to my scripts:

Code:
installed() {

    cmd=$(command -v "${1}")

    [[ -n "${cmd}" ]] && [[ -f "${cmd}" ]]

    return ${?}

}

installed "gcc" || { echo "I need gcc."; exit 1; }

I used to use "which" for the same purpose, but the fact that OS X's version is slightly different was a source of great annoyance when scripting.

https://keybase.io/yossarian
https://github.com/woodruffw
#etc @ rizon

	venam Offline \| 06-06-2017, 01:13 PM \| #6

There seem to be a confusion with some users (neeasade and jkl). When I mentioned "not posix" I didn't mean "not Unix-like".

	jkl Offline \| 06-06-2017, 01:17 PM \| #7

Sorry, that was new to me.

--
<mort> choosing a terrible license just to be spiteful towards others is possibly the most tux0r thing I've ever seen

	venam Offline \| 06-06-2017, 01:26 PM \| #8

(06-06-2017, 01:17 PM)jkl Wrote: Sorry, that was new to me.

Neeasade had posted a whole "block" about some other OS too, don't be sorry about that.

	venam Offline \| 23-11-2021, 01:45 PM \| #9

A recent blog post reminded me of this: https://www.madebygps.com/an-intro-to-fi...-in-linux/

	neeasade Offline \| 29-11-2021, 02:03 PM \| #10

tangently-related: Sometimes in my dotfiles I will wrap a program with some opinionated behavior (EG dmenu, or mpv). When that happens, I need a way to call the original program/fix the name collision. Enter the script `og`:

Code:
#!/bin/sh

# call the original version of some thing in $PATH

og=$1

shift

"$(type -a "$og" | tail -n 1 | sed -E "s/${og}//;s/ is //;")" "$@"

Then, in my 'wrapped' ~/bin/mpv, I can do something like:

Code:
og mpv \

   --write-filename-in-watch-later-config \

   --save-position-on-quit \

   "$@"

	z3bra Offline \| 29-11-2021, 07:50 PM \| #11

I don't know which shell you're using, but you can do the same by prefixing the command with \ in most shells (even dash(1)):

Code:
% alias ls='ls -l'

% ls

code

data

tmp

% \ls

code data tmp

	neeasade Offline \| 30-11-2021, 02:26 AM \| #12

The shell is bash, in a scripting context -- and the \ trick is a fair callout for escaping aliases in an interactive context for sure!

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