Extract filename and extension in Bash

Question

I want to get the filename (without extension) and the extension separately.

The best solution I found so far is:

NAME=`echo \"$FILE\" | cut -d\'.\'          


        

Answer 1

pax> echo a.b.js | sed 's/\.[^.]*$//'
a.b
pax> echo a.b.js | sed 's/^.*\.//'
js

works fine, so you can just use:

pax> FILE=a.b.js
pax> NAME=$(echo "$FILE" | sed 's/\.[^.]*$//')
pax> EXTENSION=$(echo "$FILE" | sed 's/^.*\.//')
pax> echo $NAME
a.b
pax> echo $EXTENSION
js

The commands, by the way, work as follows.

The command for NAME substitutes a "." character followed by any number of non-"." characters up to the end of the line, with nothing (i.e., it removes everything from the final "." to the end of the line, inclusive). This is basically a non-greedy substitution using regex trickery.

The command for EXTENSION substitutes a any number of characters followed by a "." character at the start of the line, with nothing (i.e., it removes everything from the start of the line to the final dot, inclusive). This is a greedy substitution which is the default action.

Answer 2

Here is the algorithm I used for finding the name and extension of a file when I wrote a Bash script to make names unique when names conflicted with respect to casing.

#! /bin/bash 

#
# Finds 
# -- name and extension pairs
# -- null extension when there isn't an extension.
# -- Finds name of a hidden file without an extension
# 

declare -a fileNames=(
  '.Montreal' 
  '.Rome.txt' 
  'Loundon.txt' 
  'Paris' 
  'San Diego.txt'
  'San Francisco' 
  )

echo "Script ${0} finding name and extension pairs."
echo 

for theFileName in "${fileNames[@]}"
do
     echo "theFileName=${theFileName}"  

     # Get the proposed name by chopping off the extension
     name="${theFileName%.*}"

     # get extension.  Set to null when there isn't an extension
     # Thanks to mklement0 in a comment above.
     extension=$([[ "$theFileName" == *.* ]] && echo ".${theFileName##*.}" || echo '')

     # a hidden file without extenson?
     if [ "${theFileName}" = "${extension}" ] ; then
         # hidden file without extension.  Fixup.
         name=${theFileName}
         extension=""
     fi

     echo "  name=${name}"
     echo "  extension=${extension}"
done 

The test run.

$ config/Name\&Extension.bash 
Script config/Name&Extension.bash finding name and extension pairs.

theFileName=.Montreal
  name=.Montreal
  extension=
theFileName=.Rome.txt
  name=.Rome
  extension=.txt
theFileName=Loundon.txt
  name=Loundon
  extension=.txt
theFileName=Paris
  name=Paris
  extension=
theFileName=San Diego.txt
  name=San Diego
  extension=.txt
theFileName=San Francisco
  name=San Francisco
  extension=
$ 

FYI: The complete transliteration program and more test cases can be found here: https://www.dropbox.com/s/4c6m0f2e28a1vxf/avoid-clashes-code.zip?dl=0

Answer 3

You could use the cut command to remove the last two extensions (the ".tar.gz" part):

$ echo "foo.tar.gz" | cut -d'.' --complement -f2-
foo

---

As noted by Clayton Hughes in a comment, this will not work for the actual example in the question. So as an alternative I propose using sed with extended regular expressions, like this:

$ echo "mpc-1.0.1.tar.gz" | sed -r 's/\.[[:alnum:]]+\.[[:alnum:]]+$//'
mpc-1.0.1

It works by removing the last two (alpha-numeric) extensions unconditionally.

[Updated again after comment from Anders Lindahl]

Answer 4

That doesn't seem to work if the file has no extension, or no filename. Here is what I'm using; it only uses builtins and handles more (but not all) pathological filenames.

#!/bin/bash
for fullpath in "$@"
do
    filename="${fullpath##*/}"                      # Strip longest match of */ from start
    dir="${fullpath:0:${#fullpath} - ${#filename}}" # Substring from 0 thru pos of filename
    base="${filename%.[^.]*}"                       # Strip shortest match of . plus at least one non-dot char from end
    ext="${filename:${#base} + 1}"                  # Substring from len of base thru end
    if [[ -z "$base" && -n "$ext" ]]; then          # If we have an extension and no base, it's really the base
        base=".$ext"
        ext=""
    fi

    echo -e "$fullpath:\n\tdir  = \"$dir\"\n\tbase = \"$base\"\n\text  = \"$ext\""
done

And here are some testcases:

$ basename-and-extension.sh / /home/me/ /home/me/file /home/me/file.tar /home/me/file.tar.gz /home/me/.hidden /home/me/.hidden.tar /home/me/.. .
/:
    dir  = "/"
    base = ""
    ext  = ""
/home/me/:
    dir  = "/home/me/"
    base = ""
    ext  = ""
/home/me/file:
    dir  = "/home/me/"
    base = "file"
    ext  = ""
/home/me/file.tar:
    dir  = "/home/me/"
    base = "file"
    ext  = "tar"
/home/me/file.tar.gz:
    dir  = "/home/me/"
    base = "file.tar"
    ext  = "gz"
/home/me/.hidden:
    dir  = "/home/me/"
    base = ".hidden"
    ext  = ""
/home/me/.hidden.tar:
    dir  = "/home/me/"
    base = ".hidden"
    ext  = "tar"
/home/me/..:
    dir  = "/home/me/"
    base = ".."
    ext  = ""
.:
    dir  = ""
    base = "."
    ext  = ""

Answer 5

Ok so if I understand correctly, the problem here is how to get the name and the full extension of a file that has multiple extensions, e.g., stuff.tar.gz.

This works for me:

fullfile="stuff.tar.gz"
fileExt=${fullfile#*.}
fileName=${fullfile%*.$fileExt}

This will give you stuff as filename and .tar.gz as extension. It works for any number of extensions, including 0. Hope this helps for anyone having the same problem =)

Answer 6

Simply use ${parameter%word}

In your case:

${FILE%.*}

If you want to test it, all following work, and just remove the extension:

FILE=abc.xyz; echo ${FILE%.*};
FILE=123.abc.xyz; echo ${FILE%.*};
FILE=abc; echo ${FILE%.*};