bash/fish command to print absolute path to a file

Question

Question: is there a simple sh/bash/zsh/fish/... command to print the absolute path of whichever file I feed it?

Usage case: I'm in directory /a/b and I'd like to print the full path to file c on the command-line so that I can easily paste it into another program: /a/b/c. Simple, yet a little program to do this could probably save me 5 or so seconds when it comes to handling long paths, which in the end adds up. So it surprises me that I can't find a standard utility to do this — is there really none?

Here's a sample implementation, abspath.py:

#!/usr/bin/python
# Author: Diggory Hardy <[e-mail]>
# Licence: public domain
# Purpose: print the absolute path of all input paths

import sys
import os.path
if len(sys.argv)>1:
    for i in range(1,len(sys.argv)):
        print os.path.abspath( sys.argv[i] )
    sys.exit(0)
else:
    print >> sys.stderr, "Usage: ",sys.argv[0]," PATH."
    sys.exit(1)

Answer 1

An alternative to get the absolute path in Ruby:

realpath() {ruby -e "require 'Pathname'; puts Pathname.new('$1').realpath.to_s";}

Works with no arguments (current folder) and relative and absolute file or folder path as agument.

Answer 2

This relative path to absolute path converter shell function

• requires no utilities (just cd and pwd)
• works for directories and files
• handles .. and .
• handles spaces in dir or filenames
• requires that file or directory exists
• returns nothing if nothing exists at the given path
• handles absolute paths as input (passes them through essentially)

Code:

function abspath() {
    # generate absolute path from relative path
    # $1     : relative filename
    # return : absolute path
    if [ -d "$1" ]; then
        # dir
        (cd "$1"; pwd)
    elif [ -f "$1" ]; then
        # file
        if [[ $1 = /* ]]; then
            echo "$1"
        elif [[ $1 == */* ]]; then
            echo "$(cd "${1%/*}"; pwd)/${1##*/}"
        else
            echo "$(pwd)/$1"
        fi
    fi
}

Sample:

# assume inside /parent/cur
abspath file.txt        => /parent/cur/file.txt
abspath .               => /parent/cur
abspath ..              => /parent
abspath ../dir/file.txt => /parent/dir/file.txt
abspath ../dir/../dir   => /parent/dir          # anything cd can handle
abspath doesnotexist    =>                      # empty result if file/dir does not exist
abspath /file.txt       => /file.txt            # handle absolute path input

Note: This is based on the answers from nolan6000 and bsingh, but fixes the file case.

I also understand that the original question was about an existing command line utility. But since this seems to be THE question on stackoverflow for that including shell scripts that want to have minimal dependencies, I put this script solution here, so I can find it later :)

Answer 3

For directories dirname gets tripped for ../ and returns ./.

nolan6000's function can be modified to fix that:

get_abs_filename() {
  # $1 : relative filename
  if [ -d "${1%/*}" ]; then
    echo "$(cd ${1%/*}; pwd)/${1##*/}"
  fi
}

Answer 4

The dogbane answer with the description what is coming on:

#! /bin/sh
echo "$(cd "$(dirname "$1")"; pwd)/$(basename "$1")"

Explanation:

1. This script get relative path as argument "$1"
2. Then we get dirname part of that path (you can pass either dir or file to this script): dirname "$1"
3. Then we cd "$(dirname "$1") into this relative dir and get absolute path for it by running pwd shell command
4. After that we append basename to absolute path: $(basename "$1")
5. As final step we echo it

Answer 5

This is not an answer to the question, but for those who does scripting:

echo `cd "$1" 2>/dev/null&&pwd||(cd "$(dirname "$1")";pwd|sed "s|/*\$|/${1##*/}|")`

it handles / .. ./ etc correctly. I also seems to work on OSX

Answer 6

Try readlink which will resolve symbolic links:

readlink -e /foo/bar/baz