Get the source directory of a Bash script from within the script itself

StackOverflow https://stackoverflow.com/questions/59895

  •  09-06-2019
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Question

How do I get the path of the directory in which a Bash script is located, inside that script?

For instance, let's say I want to use a Bash script as a launcher for another application. I want to change the working directory to the one where the Bash script is located, so I can operate on the files in that directory, like so: 

$ ./application
Was it helpful?

Solution 

#!/bin/bash

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"

is a useful one-liner which will give you the full directory name of the script no matter where it is being called from.

It will work as long as the last component of the path used to find the script is not a symlink (directory links are OK). If you also want to resolve any links to the script itself, you need a multi-line solution:

#!/bin/bash

SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
  DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
  SOURCE="$(readlink "$SOURCE")"
  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
done
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"

This last one will work with any combination of aliases, source, bash -c, symlinks, etc.

Beware: if you cd to a different directory before running this snippet, the result may be incorrect!

Also, watch out for $CDPATH gotchas, and stderr output side effects if the user has smartly overridden cd to redirect output to stderr instead (including escape sequences, such as when calling update_terminal_cwd >&2 on Mac). Adding >/dev/null 2>&1 at the end of your cd command will take care of both possibilities.

To understand how it works, try running this more verbose form:

#!/bin/bash

SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
  TARGET="$(readlink "$SOURCE")"
  if [[ $TARGET == /* ]]; then
    echo "SOURCE '$SOURCE' is an absolute symlink to '$TARGET'"
    SOURCE="$TARGET"
  else
    DIR="$( dirname "$SOURCE" )"
    echo "SOURCE '$SOURCE' is a relative symlink to '$TARGET' (relative to '$DIR')"
    SOURCE="$DIR/$TARGET" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
  fi
done
echo "SOURCE is '$SOURCE'"
RDIR="$( dirname "$SOURCE" )"
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
if [ "$DIR" != "$RDIR" ]; then
  echo "DIR '$RDIR' resolves to '$DIR'"
fi
echo "DIR is '$DIR'"

And it will print something like:

SOURCE './scriptdir.sh' is a relative symlink to 'sym2/scriptdir.sh' (relative to '.')
SOURCE is './sym2/scriptdir.sh'
DIR './sym2' resolves to '/home/ubuntu/dotfiles/fo fo/real/real1/real2'
DIR is '/home/ubuntu/dotfiles/fo fo/real/real1/real2'

OTHER TIPS

Use dirname "$0":

#!/bin/bash
echo "The script you are running has basename `basename "$0"`, dirname `dirname "$0"`"
echo "The present working directory is `pwd`"

using pwd alone will not work if you are not running the script from the directory it is contained in.

[matt@server1 ~]$ pwd
/home/matt
[matt@server1 ~]$ ./test2.sh
The script you are running has basename test2.sh, dirname .
The present working directory is /home/matt
[matt@server1 ~]$ cd /tmp
[matt@server1 tmp]$ ~/test2.sh
The script you are running has basename test2.sh, dirname /home/matt
The present working directory is /tmp

The dirname command is the most basic, simply parsing the path up to the filename off of the $0 (script name) variable:

dirname "$0"

But, as matt b pointed out, the path returned is different depending on how the script is called. pwd doesn't do the job because that only tells you what the current directory is, not what directory the script resides in. Additionally, if a symbolic link to a script is executed, you're going to get a (probably relative) path to where the link resides, not the actual script.

Some others have mentioned the readlink command, but at its simplest, you can use:

dirname "$(readlink -f "$0")"

readlink will resolve the script path to an absolute path from the root of the filesystem. So, any paths containing single or double dots, tildes and/or symbolic links will be resolved to a full path.

Here's a script demonstrating each of these, whatdir.sh:

#!/bin/bash
echo "pwd: `pwd`"
echo "\$0: $0"
echo "basename: `basename $0`"
echo "dirname: `dirname $0`"
echo "dirname/readlink: $(dirname $(readlink -f $0))"

Running this script in my home dir, using a relative path:

>>>$ ./whatdir.sh 
pwd: /Users/phatblat
$0: ./whatdir.sh
basename: whatdir.sh
dirname: .
dirname/readlink: /Users/phatblat

Again, but using the full path to the script:

>>>$ /Users/phatblat/whatdir.sh 
pwd: /Users/phatblat
$0: /Users/phatblat/whatdir.sh
basename: whatdir.sh
dirname: /Users/phatblat
dirname/readlink: /Users/phatblat

Now changing directories:

>>>$ cd /tmp
>>>$ ~/whatdir.sh 
pwd: /tmp
$0: /Users/phatblat/whatdir.sh
basename: whatdir.sh
dirname: /Users/phatblat
dirname/readlink: /Users/phatblat

And finally using a symbolic link to execute the script:

>>>$ ln -s ~/whatdir.sh whatdirlink.sh
>>>$ ./whatdirlink.sh 
pwd: /tmp
$0: ./whatdirlink.sh
basename: whatdirlink.sh
dirname: .
dirname/readlink: /Users/phatblat

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

Works for all versions,including

  • when called via multple depth soft link,
  • when the file it
  • when script called by command "source" aka . (dot) operator.
  • when arg $0 is modified from caller.
  • "./script"
  • "/full/path/to/script"
  • "/some/path/../../another/path/script"
  • "./some/folder/script"

Alternatively, if the bash script itself is a relative symlink you want to follow it and return the full path of the linked-to script:

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

SCRIPT_PATH is given in full path, no matter how it is called.
Just make sure you locate this at start of the script.

This comment and code Copyleft, selectable license under the GPL2.0 or later or CC-SA 3.0 (CreativeCommons Share Alike) or later. (c) 2008. All rights reserved. No warranty of any kind. You have been warned.
http://www.gnu.org/licenses/gpl-2.0.txt
http://creativecommons.org/licenses/by-sa/3.0/
18eedfe1c99df68dc94d4a94712a71aaa8e1e9e36cacf421b9463dd2bbaa02906d0d6656

Short answer:

`dirname $0`

or (preferably):

$(dirname "$0")

You can use $BASH_SOURCE

#!/bin/bash

scriptdir=`dirname "$BASH_SOURCE"`

Note that you need to use #!/bin/bash and not #!/bin/sh since its a bash extension

This should do it:

DIR=$(dirname "$(readlink -f "$0")")

Works with symlinks and spaces in path. See man pages for dirname and readlink.

Edit:

From the comment track it seems not to work with Mac OS. I have no idea why that is. Any suggestions?

pwd can be used to find the current working directory, and dirname to find the directory of a particular file (command that was run, is $0, so dirname $0 should give you the directory of the current script).

However, dirname gives precisely the directory portion of the filename, which more likely than not is going to be relative to the current working directory. If your script needs to change directory for some reason, then the output from dirname becomes meaningless.

I suggest the following:

#!/bin/bash

reldir=`dirname $0`
cd $reldir
directory=`pwd`

echo "Directory is $directory"

This way, you get an absolute, rather then relative directory.

Since the script will be run in a separate bash instance, there is no need to restore the working directory afterwards, but if you do want to change back in your script for some reason, you can easily assign the value of pwd to a variable before you change directory, for future use.

Although just

cd `dirname $0`

solves the specific scenario in the question, I find having the absolute path to more more useful generally.

I don't think this is as easy as others have made it out to be. pwd doesn't work, as the current dir is not necessarily the directory with the script. $0 doesn't always have the info either. Consider the following three ways to invoke a script.

./script

/usr/bin/script

script

In the first and third ways $0 doesn't have the full path info. In the second and third, pwd do not work. The only way to get the dir in the third way would be to run through the path and find the file with the correct match. Basically the code would have to redo what the OS does.

One way to do what you are asking would be to just hardcode the data in the /usr/share dir, and reference it by full path. Data shoudn't be in the /usr/bin dir anyway, so this is probably the thing to do.

SCRIPT_DIR=$( cd ${0%/*} && pwd -P )

This gets the current working directory on Mac OS X 10.6.6:

DIR=$(cd "$(dirname "$0")"; pwd)

$(dirname "$(readlink -f "$BASH_SOURCE")")

I am tired of coming to this page over and over to copy paste the one-liner in the accepted answer. The problem with that is it is not easy to understand and remember.

Here is an easy-to-remember script:

DIR=$(dirname "${BASH_SOURCE[0]}")  # get the directory name
DIR=$(realpath "${DIR}")    # resolve its full path if need be

This is Linux specific, but you could use:

SELF=$(readlink /proc/$$/fd/255)

Here is a POSIX compliant one-liner:

SCRIPT_PATH=`dirname "$0"`; SCRIPT_PATH=`eval "cd \"$SCRIPT_PATH\" && pwd"`

# test
echo $SCRIPT_PATH

I tried every one of these and none of them worked. One was very close but had a tiny bug that broke it badly; they forgot to wrap the path in quotation marks.

Also a lot of people assume you're running the script from a shell so forget when you open a new script it defaults to your home.

Try this directory on for size:

/var/No one/Thought/About Spaces Being/In a Directory/Name/And Here's your file.text

This gets it right regardless how or where you run it.

#!/bin/bash
echo "pwd: `pwd`"
echo "\$0: $0"
echo "basename: `basename "$0"`"
echo "dirname: `dirname "$0"`"

So to make it actually useful here's how to change to the directory of the running script:

cd "`dirname "$0"`"

Hope that helps

Here is the simple, correct way:

actual_path=$(readlink -f "${BASH_SOURCE[0]}")
script_dir=$(dirname "$actual_path")

Explanation:

  • ${BASH_SOURCE[0]} - the full path to the script. The value of this will be correct even when the script is being sourced, e.g. source <(echo 'echo $0') prints bash, while replacing it with ${BASH_SOURCE[0]} will print the full path of the script. (Of course, this assumes you're OK taking a dependency on Bash.)

  • readlink -f - Recursively resolves any symlinks in the specified path. This is a GNU extension, and not available on (for example) BSD systems. If you're running a Mac, you can use Homebrew to install GNU coreutils and supplant this with greadlink -f.

  • And of course dirname gets the parent directory of the path.

I would use something like this:

# retrieve the full pathname of the called script
scriptPath=$(which $0)

# check whether the path is a link or not
if [ -L $scriptPath ]; then

    # it is a link then retrieve the target path and get the directory name
    sourceDir=$(dirname $(readlink -f $scriptPath))

else

    # otherwise just get the directory name of the script path
    sourceDir=$(dirname $scriptPath)

fi

A slight revision to the solution e-satis and 3bcdnlklvc04a pointed out in their answer

SCRIPT_DIR=''
pushd "$(dirname "$(readlink -f "$BASH_SOURCE")")" > /dev/null && {
    SCRIPT_DIR="$PWD"
    popd > /dev/null
}

This should still work in all the cases they listed.

EDIT: prevent popd after failed pushd, thanks to konsolebox

#!/bin/sh
PRG="$0"

# need this for relative symlinks
while [ -h "$PRG" ] ; do
   PRG=`readlink "$PRG"`
done

scriptdir=`dirname "$PRG"`

$_ is worth mentioning as an alternative to $0. If you're running a script from bash, the accepted answer can be shortened to:

DIR="$( dirname "$_" )"

Note that this has to be the first statement in your script.

I've compared many of the answers given, and come up with some more compact solutions. These seem to handle all of the crazy edge cases that arise from your favorite combination of:

  • Absolute paths or relative paths
  • File and directory soft links
  • Invocation as script, bash script, bash -c script, source script, or . script
  • Spaces, tabs, newlines, unicode, etc. in directories and/or filename
  • Filenames beginning with a hyphen

If you're running from Linux, it seems that using the proc handle is the best solution to locate the fully resolved source of the currently running script (in an interactive session, the link points to the respective /dev/pts/X):

resolved="$(readlink /proc/$$/fd/255 && echo X)" && resolved="${resolved%$'\nX'}"

This has a small bit of ugliness to it, but the fix is compact and easy to understand. We aren't using bash primitives only, but I'm okay with that because readlink simplifies the task considerably. The echo X adds an X to the end of the variable string so that any trailing whitespace in the filename doesn't get eaten, and the parameter substitution ${VAR%X} at the end of the line gets rid of the X. Because readlink adds a newline of its own (which would normally be eaten in the command substitution if not for our previous trickery), we have to get rid of that, too. This is most easily accomplished using the $'' quoting scheme, which lets us use escape sequences such as \n to represent newlines (this is also how you can easily make deviously named directories and files).

The above should cover your needs for locating the currently running script on Linux, but if you don't have the proc filesystem at your disposal, or if you're trying to locate the fully resolved path of some other file, then maybe you'll find the below code helpful. It's only a slight modification from the above one-liner. If you're playing around with strange directory/filenames, checking the output with both ls and readlink is informative, as ls will output "simplified" paths, substituting ? for things like newlines.

absolute_path=$(readlink -e -- "${BASH_SOURCE[0]}" && echo x) && absolute_path=${absolute_path%?x}
dir=$(dirname -- "$absolute_path" && echo x) && dir=${dir%?x}
file=$(basename -- "$absolute_path" && echo x) && file=${file%?x}

ls -l -- "$dir/$file"
printf '$absolute_path: "%s"\n' "$absolute_path"

Try using:

real=$(realpath $(dirname $0))

For systems having GNU coreutils readlink (eg. linux):

$(readlink -f "$(dirname "$0")")

No need to use BASH_SOURCE when $0 contains the script filename.

So... I believe I've got this one. Late to the party, but I think some will appreciate it being here is them come across this thread. The comments should explain.

#!/bin/sh # dash bash ksh # !zsh (issues). G. Nixon, 12/2013. Public domain.

## 'linkread' or 'fullpath' or (you choose) is a little tool to recursively
## dereference symbolic links (ala 'readlink') until the originating file
## is found. This is effectively the same function provided in stdlib.h as
## 'realpath' and on the command line in GNU 'readlink -f'.

## Neither of these tools, however, are particularly accessible on the many
## systems that do not have the GNU implementation of readlink, nor ship
## with a system compiler (not to mention the requisite knowledge of C).

## This script is written with portability and (to the extent possible, speed)
## in mind, hence the use of printf for echo and case statements where they
## can be substituded for test, though I've had to scale back a bit on that.

## It is (to the best of my knowledge) written in standard POSIX shell, and
## has been tested with bash-as-bin-sh, dash, and ksh93. zsh seems to have
## issues with it, though I'm not sure why; so probably best to avoid for now.

## Particularly useful (in fact, the reason I wrote this) is the fact that
## it can be used within a shell script to find the path of the script itself.
## (I am sure the shell knows this already; but most likely for the sake of
## security it is not made readily available. The implementation of "$0"
## specificies that the $0 must be the location of **last** symbolic link in
## a chain, or wherever it resides in the path.) This can be used for some
## ...interesting things, like self-duplicating and self-modifiying scripts.

## Currently supported are three errors: whether the file specified exists
## (ala ENOENT), whether its target exists/is accessible; and the special
## case of when a sybolic link references itself "foo -> foo": a common error
## for beginners, since 'ln' does not produce an error if the order of link
## and target are reversed on the command line. (See POSIX signal ELOOP.)

## It would probably be rather simple to write to use this as a basis for
## a pure shell implementation of the 'symlinks' util included with Linux.

## As an aside, the amount of code below **completely** belies the amount
## effort it took to get this right -- but I guess that's coding for you.

##===-------------------------------------------------------------------===##

for argv; do :; done # Last parameter on command line, for options parsing.

## Error messages. Use functions so that we can sub in when the error occurs.

recurses(){ printf "Self-referential:\n\t$argv ->\n\t$argv\n" ;}
dangling(){ printf "Broken symlink:\n\t$argv ->\n\t"$(readlink "$argv")"\n" ;}
errnoent(){ printf "No such file: "$@"\n" ;} # Borrow a horrible signal name.

# Probably best not to install as 'pathfull', if you can avoid it.

pathfull(){ cd "$(dirname "$@")"; link="$(readlink "$(basename "$@")")"

## 'test and 'ls' report different status for bad symlinks, so we use this.

 if [ ! -e "$@" ]; then if $(ls -d "$@" 2>/dev/null) 2>/dev/null;  then
    errnoent 1>&2; exit 1; elif [ ! -e "$@" -a "$link" = "$@" ];   then
    recurses 1>&2; exit 1; elif [ ! -e "$@" ] && [ ! -z "$link" ]; then
    dangling 1>&2; exit 1; fi
 fi

## Not a link, but there might be one in the path, so 'cd' and 'pwd'.

 if [ -z "$link" ]; then if [ "$(dirname "$@" | cut -c1)" = '/' ]; then
   printf "$@\n"; exit 0; else printf "$(pwd)/$(basename "$@")\n"; fi; exit 0
 fi

## Walk the symlinks back to the origin. Calls itself recursivly as needed.

 while [ "$link" ]; do
   cd "$(dirname "$link")"; newlink="$(readlink "$(basename "$link")")"
   case "$newlink" in
    "$link") dangling 1>&2 && exit 1                                       ;;
         '') printf "$(pwd)/$(basename "$link")\n"; exit 0                 ;;
          *) link="$newlink" && pathfull "$link"                           ;;
   esac
 done
 printf "$(pwd)/$(basename "$newlink")\n"
}

## Demo. Install somewhere deep in the filesystem, then symlink somewhere 
## else, symlink again (maybe with a different name) elsewhere, and link
## back into the directory you started in (or something.) The absolute path
## of the script will always be reported in the usage, along with "$0".

if [ -z "$argv" ]; then scriptname="$(pathfull "$0")"

# Yay ANSI l33t codes! Fancy.
 printf "\n\033[3mfrom/as: \033[4m$0\033[0m\n\n\033[1mUSAGE:\033[0m   "
 printf "\033[4m$scriptname\033[24m [ link | file | dir ]\n\n         "
 printf "Recursive readlink for the authoritative file, symlink after "
 printf "symlink.\n\n\n         \033[4m$scriptname\033[24m\n\n        "
 printf " From within an invocation of a script, locate the script's "
 printf "own file\n         (no matter where it has been linked or "
 printf "from where it is being called).\n\n"

else pathfull "$@"
fi

Try the following cross-compatible solution:

CWD="$(cd -P -- "$(dirname -- "$0")" && pwd -P)"

as realpath or readlink commands are not always available (depending on the operating system) and ${BASH_SOURCE[0]} is available only in bash shell.

Alternatively you can try the following function in bash:

realpath () {
  [[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}

This function takes 1 argument. If argument has already absolute path, print it as it is, otherwise print $PWD variable + filename argument (without ./ prefix).

Related:

Hmm, if in the path basename & dirname are just not going to cut it and walking the path is hard (what if parent didn't export PATH!). However, the shell has to have an open handle to its script, and in bash the handle is #255.

SELF=`readlink /proc/$$/fd/255`

works for me.

To sum up many answers:

    Script: "/tmp/src dir/test.sh"
    Calling folder: "/tmp/src dir/other"

Used Commands

    echo Script-Dir : `dirname "$(realpath $0)"`
    echo Script-Dir : $( cd ${0%/*} && pwd -P )
    echo Script-Dir : $(dirname "$(readlink -f "$0")")
    echo
    echo Script-Name : `basename "$(realpath $0)"`
    echo Script-Name : `basename $0`
    echo
    echo Script-Dir-Relative : `dirname "$BASH_SOURCE"`
    echo Script-Dir-Relative : `dirname $0`
    echo
    echo Calling-Dir : `pwd`

The output:

     Script-Dir : /tmp/src dir
     Script-Dir : /tmp/src dir
     Script-Dir : /tmp/src dir

     Script-Name : test.sh
     Script-Name : test.sh

     Script-Dir-Relative : ..
     Script-Dir-Relative : ..

     Calling-Dir : /tmp/src dir/other

See https://pastebin.com/J8KjxrPF

This works in bash-3.2:

path="$( dirname "$( which "$0" )" )"

Here's an example of its usage:

Say you have a ~/bin directory, which is in your $PATH. You have script A inside this directory. It sources script ~/bin/lib/B. You know where the included script is relative to the original one (the subdirectory lib), but not where it is relative to the user's current directory.

This is solved by the following (inside A):

source "$( dirname "$( which "$0" )" )/lib/B"

It doesn't matter where the user is or how he calls the script, this will always work.

None of these worked for a bash script launched by Finder in OS X - I ended up using:

SCRIPT_LOC="`ps -p $$ | sed /PID/d | sed s:.*/Network/:/Network/: |
sed s:.*/Volumes/:/Volumes/:`"

Not pretty, but it gets the job done.

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