bashdirectory

How do I get the directory where a Bash script is located from within the script itself?


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

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

Solution

  • #!/usr/bin/env bash
    
    SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && 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:

    #!/usr/bin/env bash
    
    SOURCE=${BASH_SOURCE[0]}
    while [ -L "$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:

    #!/usr/bin/env bash
    
    SOURCE=${BASH_SOURCE[0]}
    while [ -L "$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'