shell script relative position from the file

Question

I have almost no idea about shell scripts or commands in linux

I have a project named projectx

projectX happens to be in users/hardik/desktop/projectx

I have created a shell script start.sh. This is the content of shell script

echo "Starting typescript build in new terminal.."
osascript -e 'tell application "Terminal" to do script "npm run build"'
sleep 3
echo "Starting firebase functions...."
osascript -e 'tell application "Terminal" to do script "firebase emulators:start --only functions"'
echo "Process compelete.. Check if there were two terminals window open"

now this works but say here

osascript -e 'tell application "Terminal" to do script "npm run build"'

it runs that in the root and hence gives the following error

ENOENT: no such file or directory, open /Users/hardik/package.json

How can I make it execute in the path which is relative to start.sh

Update: I tried these but it didn't work

cd "$(dirname $(readlink -f "$0"))"
echo "Starting typescript build in new terminal.."
osascript -e 'tell application "Terminal" to do script "npm run watch:scss"' 
osascript -e 'tell application "Terminal" to do script "npm run watch"'
echo "Process compelete.. Check if there were two terminals window open"

This is what it logs for the above

readlink: illegal option -- f
usage: readlink [-n] [file ...]
usage: dirname path
Starting typescript build in new terminal..
tab 1 of window id 1579
tab 1 of window id 1580

also the below snippet doesn't work either

cd -P -- "${0%/*}" || exit
echo "Starting typescript build in new terminal.."
osascript -e 'tell application "Terminal" to do script "npm run watch:scss"' 
osascript -e 'tell application "Terminal" to do script "npm run watch"'
echo "Process compelete.. Check if there were two terminals window open"

Same error

@glennjackman npm watch. I want one command to start everything. Since both of them are watch, they might also throw error if something goes wrong. for that, I don't want things to happen in the same terminal and I also don't want to run two npm commands whenever I start a project. — iRohitBhatia, Jun 30 '20 at 21:34
Possibly helpful (but I can't say whether it works on macOS): https://unix.stackexchange.com/a/50392/315749 — fra-san, Jul 01 '20 at 22:08

score 1 · Answer 1 · edited Jun 30 '20 at 15:17

1

You can add cd -P -- "${0%/*}" || exit or cd -P -- "$(dirname -- "$0")" || exit to your script to jump into the directory in which the script resides.

$0 is a built-in variable holding the path of the script as given to the interpreter (will typically be an absolute path if the script was looked up in $PATH).

The ${0%/*} construct uses the shell's built-in String Manipulation to remove from the end the shortest bit of the variable matching /*, which leaves you with just the directory name (would work as long as $0 contains at least one / character which is generally the case).

edited Jun 30 '20 at 15:17

Stéphane Chazelas

544,893

answered Jun 30 '20 at 14:46

user420417

11

1

$0 doesn't always contain the full name of the script, it generally contains the name used to invoke the script. – Andy Dalton Jun 30 '20 at 14:58
Right, but if it's in your path, $0 is set to the full path. Otherwise you specify either the absolute or relative path, and cd will still succeed in putting you into that absolute or relative path. – user420417 Jun 30 '20 at 15:03
But nothing in the OP suggests that his script is in his path. – Andy Dalton Jun 30 '20 at 15:23
@user420417 I tried what you said based on my underdstanding. Didn't work (updated question for the same) – iRohitBhatia Jun 30 '20 at 21:36
You may use something as if [ "$0" = "${0#/*}" ]; then mypath=${PWD}/${0%/*}; else mypath=${0%/*}; fi to also deal with the sh script kind of invocation (that has no slash in "$0"). And (though I don't know whether it's supported on macOS) readlink -f "$0" to handle the case of a script invoked as a symbolic link. – fra-san Jul 01 '20 at 22:16

score 0 · Answer 2 · answered Jul 01 '20 at 20:38

I do not know whether this works under MacOS; it does under Linux:

#! /bin/bash
arg1="$(awk 'BEGIN { RS="\0" }; NR==2 { print $0 "x"; exit; }' /proc/$$/cmdline; echo x)"
arg1="${arg1%x}"
if [[ $arg1 =~ / ]]; then
    # path contains at least one /
    dir_rel_path="${arg1%/*}"
    cd "$dir_rel_path"
fi
echo "$PWD"

shell script relative position from the file

2 Answers2