Bdtyktl

I'm looking for a simple command that can be used within Bash to find the absolute and canonicalized path to a file on an OS X (similar to ``readlink -f'` under Linux).

The following sample bash session describes a [fictitious] utility called ``abspath'` that exhibits the desired behavior:

$ pwd

/Users/guyfleegman



$ ls -lR

drwxr-xr-x  4 guyfleegman  crew  136 Oct 30 02:09 foo



./foo:

-rw-r--r--  1 guyfleegman  crew  0 Oct 30 02:07 bar.txt

lrwxr-xr-x  1 guyfleegman  crew  7 Oct 30 02:09 baz.txt -> bar.txt





$ abspath .

/Users/guyfleegman



$ abspath foo

/Users/guyfleegman/foo



$ abspath ./foo/bar.txt

/Users/guyfleegman/foo/bar.txt



$ abspath foo/baz.txt

/Users/guyfleegman/foo/baz.txt

As with the last invocation of ``abspath'` in the above example, I'd prefer it didn't automatically resolve symlinks, but I'm not going to be too picky here.

function abspath() { pushd . > /dev/null; if [ -d "$1" ]; then cd "$1"; dirs -l +0; else cd "`dirname "$1"`"; cur_dir=`dirs -l +0`; if [ "$cur_dir" == "/" ]; then echo "$cur_dir`basename "$1"`"; else echo "$cur_dir/`basename "$1"`"; fi; fi; popd > /dev/null; }

Examples:

abspath / => /



abspath /.DS_Store => /.DS_Store



abspath ~ => /Users/mschrag



cd /tmp; abspath . => /tmp



cd /; abspath .DS_Store => /.DS_Store

I don't think there's a buildin command that does this. Jesse Wilson wrote a bash script for this:

#!/bin/bash

cd -P -- "$(dirname -- "$1")" &&

printf '%sn' "$(pwd -P)/$(basename -- "$1")"

However, it does not work well for paths directly below /, such as /etc (printing //etc), as well as . and .. (printing /cwd/. in both cases). I tried modifying it, but my unsufficient bash-fu failed me.

Here's my suggestion:

#!/usr/bin/env python

import os.path

import sys



for arg in sys.argv[1:]:

    print os.path.abspath(arg)

Save as /usr/bin/abspath or something like that and make it executable. Sample output:

Servus08:~ danielbeck$ abspath .

/Users/danielbeck

Servus08:~ danielbeck$ abspath /tmp

/tmp

Servus08:~ danielbeck$ abspath Documents

/Users/danielbeck/Documents

Servus08:~ danielbeck$ abspath . /tmp Documents

/Users/danielbeck

/tmp

/Users/danielbeck/Documents

If you do want symlink resolution, change the print line like this:

    print os.path.realpath(os.path.abspath(arg))

to get this:

Servus08:~ danielbeck$ abspath . /tmp Documents

/Users/danielbeck

/private/tmp

/Users/danielbeck/Documents

One option would be to just install coreutils and use greadlink -f. It resolves symlinks and it works with /Foo/ or ~/foo.txt if they don't exist, but not with /Foo/foo.txt if /Foo/ doesn't exist.

$ brew install coreutils

$ greadlink -f /etc

/private/etc

$ greadlink -f ~/Documents/

/Users/lauri/Documents

$ greadlink -f ..

/Users

$ greadlink -f //etc/..////

/private

$ greadlink -f /Foo

/Foo

$ greadlink -f /Foo/foo.txt

$ 

This doesn't resolve symlinks, and it doesn't work with /Foo/foo.txt either.

abspath() {

  if [ -d "$1" ]; then

    ( cd "$1"; dirs -l +0 )

  else

    ( cd "$(dirname "$1")"; d=$(dirs -l +0); echo "${d%/}/${1##*/}" )

  fi

}



abspath /etc # /etc

abspath ~/Foo/foo.txt # doesn't work

abspath ~/Foo # works

abspath .

abspath ./

abspath ../

abspath ..

abspath /

abspath ~

abspath ~/

abspath ~/Documents

abspath /" '

abspath /etc/../etc/

abspath /private//etc/

abspath /private//

abspath //private # //private

abspath ./aa.txt

abspath aa.tar.gz

abspath .aa.txt

abspath /.DS_Store

abspath ~/Documents/Books/

dirs -l performs tilde expansion. dirs +0 prints only the topmost directory if there are other directories in the stack.

I guess you could do it with either python or ruby.

$ ruby -e 'puts File.expand_path("~/somepath")'

or make it a command with

#!/usr/bin/env ruby

puts File.expand_path(ARGV[0])

If you have the File::Spec module installed for perl you can just do this:

perl -MFile::Spec -e 'print File::Spec->rel2abs("../however/complex/../you/want/to.get"), "n"'

For bash/sh scripts you can use this recursive function:

canonical_readlink ()

{

    cd `dirname $1`;

    __filename=`basename $1`;

    if [ -h "$__filename" ]; then

        canonical_readlink `readlink $__filename`;

    else

        echo "`pwd -P`";

    fi

}



answer=$(canonical_readlink $0)

Install the following library for OSX:

brew install coreutils



greadlink -f file.txt