CODEWITHSUNDEEP
macosbashshellsh
Ivan Balashov
Ivan Balashov

Reputation: 1953

How to get absolute path name of shell script on MacOS?

readlink -f does not exist on MacOS. The only working solution for Mac OS I managed to find on the net goes like this:

if [[ $(echo $0 | awk '/^\//') == $0 ]]; then
    ABSPATH=$(dirname $0)
else
    ABSPATH=$PWD/$(dirname $0)
fi

Can anyone suggest anything more elegant to this seemingly trivial task?

Upvotes: 35

Views: 45625

Answers (11)

Gordon Davisson
Gordon Davisson

Reputation: 125898

Another (also rather ugly) option:

ABSPATH=$(cd "$(dirname "$0")"; pwd -P)

From pwd man page,

-P      Display the physical current working directory (all symbolic links resolved).

Upvotes: 77

Joe Linoff
Joe Linoff

Reputation: 771

I use the function below to emulate "readlink -f" for scripts that have to run on both linux and Mac OS X.

#!/bin/bash
# This was re-worked on 2018-10-26 after der@build correctly
# observed that the previous version did not work.

# Works on both linux and Mac OS X.
# The "pwd -P" re-interprets all symlinks.
function read-link() {
    local path=$1
    if [ -d $path ] ; then
        local abspath=$(cd $path; pwd -P)
    else
        local prefix=$(cd $(dirname -- $path) ; pwd -P)
        local suffix=$(basename $path)
        local abspath="$prefix/$suffix"
    fi
    if [ -e $abspath ] ; then
        echo $abspath
    else
        echo 'error: does not exist'
    fi
}

# Example usage.
while (( $# )) ; do
    printf '%-24s - ' "$1"
    read-link $1
    shift
done

This is the output for some common Mac OS X targets:

$ ./example.sh /usr/bin/which /bin/which /etc/racoon ~/Downloads
/usr/bin/which           - /usr/bin/which
/bin/which               - error: does not exist
/etc/racoon              - /private/etc/racoon
/Users/jlinoff/Downloads - /Users/jlinoff/Downloads

The is the output for some linux targets.

$ ./example.sh /usr/bin/which /bin/whichx /etc/init.d ~/Downloads
/usr/bin/which           - /usr/bin/which
/bin/whichx              - error: does not exist
/etc/init.d              - /etc/init.d
/home/jlinoff/Downloads  - /home/jlinoff/Downloads

Upvotes: 0

Lynch
Lynch

Reputation: 9474

Using bash I suggest this approach. You first cd to the directory, then you take the current directory using pwd. After that you must return to the old directory to ensure your script does not create side effects to an other script calling it.

cd "$(dirname -- "$0")"
dir="$PWD"
echo "$dir"
cd - > /dev/null

This solution is safe with complex path. You will never have troubles with spaces or special charaters if you put the quotes.

Note: the /dev/null is require or "cd -" print the path its return to.

Upvotes: 4

nhed
nhed

Reputation: 6001

Also note that homebrew's (http://brew.sh) coreutils package includes realpath (link created in/opt/local/bin).

$ realpath bin
/Users/nhed/bin

Upvotes: 3

Yoshua Wuyts
Yoshua Wuyts

Reputation: 4094

I've found this to be useful for symlinks / dynamic links - works with GNU readlink only though (because of the -f flag):

# detect if GNU readlink is available on OS X
if [ "$(uname)" = "Darwin" ]; then
  which greadlink > /dev/null || {
    printf 'GNU readlink not found\n'
    exit 1
  }
  alias readlink="greadlink"
fi

# create a $dirname variable that contains the file dir
dirname=$(dirname "$(readlink -f "$0")")

# use $dirname to find a relative file
cat "$dirname"/foo/bar.txt

Upvotes: 1

Nathan Weeks
Nathan Weeks

Reputation: 1

If you're using ksh, the ${.sh.file} parameter is set to the absolute pathname of the script. To get the parent directory of the script: ${.sh.file%/*}

Upvotes: 0

GreenFox
GreenFox

Reputation: 1122

Get absolute path of shell script

Dug out some old scripts from my .bashrc, and updated the syntax a bit, added a test suite.

Supports

  • source ./script (When called by the . dot operator)
  • Absolute path /path/to/script
  • Relative path like ./script
  • /path/dir1/../dir2/dir3/../script
  • When called from symlink
  • When symlink is nested eg) foo->dir1/dir2/bar bar->./../doe doe->script
  • When caller changes the scripts name

It has been tested and used in real projects with success, however there may be corner cases I am not aware of.
If you were able to find such a situation, please let me know.
(For one, I know that this does not run on the sh shell)

Code

pushd . > /dev/null
SCRIPT_PATH="${BASH_SOURCE[0]}";
  while([ -h "${SCRIPT_PATH}" ]) do 
    cd "`dirname "${SCRIPT_PATH}"`"
    SCRIPT_PATH="$(readlink "`basename "${SCRIPT_PATH}"`")"; 
  done
cd "`dirname "${SCRIPT_PATH}"`" > /dev/null
SCRIPT_PATH="`pwd`";
popd  > /dev/null
echo "srcipt=[${SCRIPT_PATH}]"
echo "pwd   =[`pwd`]"

Known issuse

Script must be on disk somewhere, let it be over a network. If you try to run this script from a PIPE it will not work

wget -o /dev/null -O - http://host.domain/dir/script.sh |bash

Technically speaking, it is undefined.
Practically speaking, there is no sane way to detect this.

Test case used

And the current test case that check that it works.

#!/bin/bash
# setup test enviroment
mkdir -p dir1/dir2
mkdir -p dir3/dir4
ln -s ./dir1/dir2/foo bar
ln -s ./../../dir3/dir4/test.sh dir1/dir2/foo
ln -s ./dir1/dir2/foo2 bar2
ln -s ./../../dir3/dir4/doe dir1/dir2/foo2
cp test.sh ./dir1/dir2/
cp test.sh ./dir3/dir4/
cp test.sh ./dir3/dir4/doe
P="`pwd`"
echo "--- 01"
echo "base  =[${P}]" && ./test.sh
echo "--- 02"
echo "base  =[${P}]" && `pwd`/test.sh
echo "--- 03"
echo "base  =[${P}]" && ./dir1/dir2/../../test.sh
echo "--- 04"
echo "base  =[${P}/dir3/dir4]" && ./bar
echo "--- 05"
echo "base  =[${P}/dir3/dir4]" && ./bar2
echo "--- 06"
echo "base  =[${P}/dir3/dir4]" && `pwd`/bar
echo "--- 07"
echo "base  =[${P}/dir3/dir4]" && `pwd`/bar2
echo "--- 08"
echo "base  =[${P}/dir1/dir2]" && `pwd`/dir3/dir4/../../dir1/dir2/test.sh
echo "--- 09"
echo "base  =[${P}/dir1/dir2]" && ./dir1/dir2/test.sh
echo "--- 10"
echo "base  =[${P}/dir3/dir4]" && ./dir3/dir4/doe
echo "--- 11"
echo "base  =[${P}/dir3/dir4]" && ./dir3/dir4/test.sh
echo "--- 12"
echo "base  =[${P}/dir3/dir4]" && `pwd`/dir3/dir4/doe
echo "--- 13"
echo "base  =[${P}/dir3/dir4]" && `pwd`/dir3/dir4/test.sh
echo "--- 14"
echo "base  =[${P}/dir3/dir4]" && `pwd`/dir1/dir2/../../dir3/dir4/doe
echo "--- 15"
echo "base  =[${P}/dir3/dir4]" && `pwd`/dir1/dir2/../../dir3/dir4/test.sh
echo "--- 16"
echo "base s=[${P}]" && source test.sh
echo "--- 17"
echo "base s=[${P}]" && source `pwd`/test.sh
echo "--- 18"
echo "base s=[${P}/dir1/dir2]" && source ./dir1/dir2/test.sh
echo "--- 19"
echo "base s=[${P}/dir3/dir4]" && source ./dir1/dir2/../../dir3/dir4/test.sh
echo "--- 20"
echo "base s=[${P}/dir3/dir4]" && source `pwd`/dir1/dir2/../../dir3/dir4/test.sh
echo "--- 21"
pushd . >/dev/null
cd ..
echo "base x=[${P}/dir3/dir4]"
./`basename "${P}"`/bar
popd  >/dev/null

PurpleFox aka GreenFox

Upvotes: 10

Magnus
Magnus

Reputation: 11436

This works as long as it's not a symlink, and is perhaps marginally less ugly:

ABSPATH=$(dirname $(pwd -P $0)/${0#\.\/})

Upvotes: 0

nhed
nhed

Reputation: 6001

this is what I use, may need a tweak here or there

abspath () 
{ 
    case "${1}" in 
        [./]*)
            local ABSPATH="$(cd ${1%/*}; pwd)/${1##*/}"
            echo "${ABSPATH/\/\///}"
        ;;
        *)
            echo "${PWD}/${1}"
        ;;
    esac
}

This is for any file - and of curse you can just invoke it as abspath ${0}

The first case deals with relative paths by cd-ing to the path and letting pwd figure it out

The second case is for dealing with a local file (where the ${1##/} would not have worked)

This does NOT attempt to undo symlinks!

Upvotes: 0

Barun
Barun

Reputation: 2652

Can you try something like this inside your script?

echo $(pwd)/"$0"

In my machine it shows:

/home/barun/codes/ns2/link_down/./test.sh

which is the absolute path name of the shell script.

Upvotes: 1

William Pursell
William Pursell

Reputation: 212356

If you don't mind using perl:

ABSPATH=$(perl -MCwd=realpath -e "print realpath '$0'")

Upvotes: 1

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