Extract filename and extension in Bash

First, get file name without the path:

filename=$(basename -- "$fullfile")
extension="${filename##*.}"
filename="${filename%.*}"

Alternatively, you can focus on the last '/' of the path instead of the '.' which should work even if you have unpredictable file extensions:

filename="${fullfile##*/}"

You may want to check the documentation :

On the web at section "3.5.3 Shell Parameter Expansion"

In the bash manpage at section called "Parameter Expansion"

---

~% FILE="example.tar.gz"

~% echo "${FILE%%.*}"
example

~% echo "${FILE%.*}"
example.tar

~% echo "${FILE#*.}"
tar.gz

~% echo "${FILE##*.}"
gz

For more details, see shell parameter expansion in the Bash manual.

---

Usually you already know the extension, so you might wish to use:

basename filename .extension

for example:

basename /path/to/dir/filename.txt .txt

and we get

filename

---

You can use the magic of POSIX parameter expansion:

bash-3.2$ FILENAME=somefile.tar.gz
bash-3.2$ echo "${FILENAME%%.*}"
somefile
bash-3.2$ echo "${FILENAME%.*}"
somefile.tar

There's a caveat in that if your filename was of the form ./somefile.tar.gz then echo ${FILENAME%%.*} would greedily remove the longest match to the . and you'd have the empty string.

(You can work around that with a temporary variable:

FULL_FILENAME=$FILENAME
FILENAME=${FULL_FILENAME##*/}
echo ${FILENAME%%.*}

)

This site explains more.

${variable%pattern}
  Trim the shortest match from the end
${variable##pattern}
  Trim the longest match from the beginning
${variable%%pattern}
  Trim the longest match from the end
${variable#pattern}
  Trim the shortest match from the beginning

---

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  = ""

---

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.

---

You can use basename.

Example:

$ basename foo-bar.tar.gz .tar.gz
foo-bar

You do need to provide basename with the extension that shall be removed, however if you are always executing tar with -z then you know the extension will be .tar.gz.

This should do what you want:

tar -zxvf $1
cd $(basename $1 .tar.gz)

---

Mellen writes in a comment on a blog post:

Using Bash, there’s also ${file%.*} to get the filename without the extension and ${file##*.} to get the extension alone. That is,

file="thisfile.txt"
echo "filename: ${file%.*}"
echo "extension: ${file##*.}"

Outputs:

filename: thisfile
extension: txt

---

No need to bother with awk or sed or even perl for this simple task. There is a pure-Bash, os.path.splitext()-compatible solution which only uses parameter expansions.

Reference Implementation

Documentation of os.path.splitext(path):

Split the pathname path into a pair (root, ext) such that root + ext == path, and ext is empty or begins with a period and contains at most one period. Leading periods on the basename are ignored; splitext('.cshrc') returns ('.cshrc', '').

Python code:

root, ext = os.path.splitext(path)

Bash Implementation

Honoring leading periods

root="${path%.*}"
ext="${path#"$root"}"

Ignoring leading periods

root="${path#.}";root="${path%"$root"}${root%.*}"
ext="${path#"$root"}"

Tests

Here are test cases for the Ignoring leading periods implementation, which should match the Python reference implementation on every input.

|---------------|-----------|-------|
|path           |root       |ext    |
|---------------|-----------|-------|
|' .txt'        |' '        |'.txt' |
|' .txt.txt'    |' .txt'    |'.txt' |
|' txt'         |' txt'     |''     |
|'*.txt.txt'    |'*.txt'    |'.txt' |
|'.cshrc'       |'.cshrc'   |''     |
|'.txt'         |'.txt'     |''     |
|'?.txt.txt'    |'?.txt'    |'.txt' |
|'\n.txt.txt'   |'\n.txt'   |'.txt' |
|'\t.txt.txt'   |'\t.txt'   |'.txt' |
|'a b.txt.txt'  |'a b.txt'  |'.txt' |
|'a*b.txt.txt'  |'a*b.txt'  |'.txt' |
|'a?b.txt.txt'  |'a?b.txt'  |'.txt' |
|'a\nb.txt.txt' |'a\nb.txt' |'.txt' |
|'a\tb.txt.txt' |'a\tb.txt' |'.txt' |
|'txt'          |'txt'      |''     |
|'txt.pdf'      |'txt'      |'.pdf' |
|'txt.tar.gz'   |'txt.tar'  |'.gz'  |
|'txt.txt'      |'txt'      |'.txt' |
|---------------|-----------|-------|

Test Results

All tests passed.

---

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]

---

The accepted answer works well in typical cases, but fails in edge cases, namely:

For filenames without extension (called suffix in the remainder of this answer), extension=${filename##*.} returns the input filename rather than an empty string.

extension=${filename##*.} does not include the initial ., contrary to convention. Blindly prepending . would not work for filenames without suffix.

Blindly prepending . would not work for filenames without suffix.

filename="${filename%.*}" will be the empty string, if the input file name starts with . and contains no further . characters (e.g., .bash_profile) - contrary to convention.

---------

Thus, the complexity of a robust solution that covers all edge cases calls for a function - see its definition below; it can return all components of a path.

Example call:

splitPath '/etc/bash.bashrc' dir fname fnameroot suffix
# -> $dir == '/etc'
# -> $fname == 'bash.bashrc'
# -> $fnameroot == 'bash'
# -> $suffix == '.bashrc'

Note that the arguments after the input path are freely chosen, positional variable names.
To skip variables not of interest that come before those that are, specify _ (to use throw-away variable $_) or ''; e.g., to extract filename root and extension only, use splitPath '/etc/bash.bashrc' _ _ fnameroot extension.

# SYNOPSIS
#   splitPath path varDirname [varBasename [varBasenameRoot [varSuffix]]] 
# DESCRIPTION
#   Splits the specified input path into its components and returns them by assigning
#   them to variables with the specified *names*.
#   Specify '' or throw-away variable _ to skip earlier variables, if necessary.
#   The filename suffix, if any, always starts with '.' - only the *last*
#   '.'-prefixed token is reported as the suffix.
#   As with `dirname`, varDirname will report '.' (current dir) for input paths
#   that are mere filenames, and '/' for the root dir.
#   As with `dirname` and `basename`, a trailing '/' in the input path is ignored.
#   A '.' as the very first char. of a filename is NOT considered the beginning
#   of a filename suffix.
# EXAMPLE
#   splitPath '/home/jdoe/readme.txt' parentpath fname fnameroot suffix
#   echo "$parentpath" # -> '/home/jdoe'
#   echo "$fname" # -> 'readme.txt'
#   echo "$fnameroot" # -> 'readme'
#   echo "$suffix" # -> '.txt'
#   ---
#   splitPath '/home/jdoe/readme.txt' _ _ fnameroot
#   echo "$fnameroot" # -> 'readme'  
splitPath() {
  local _sp_dirname= _sp_basename= _sp_basename_root= _sp_suffix=
    # simple argument validation
  (( $# >= 2 )) || { echo "$FUNCNAME: ERROR: Specify an input path and at least 1 output variable name." >&2; exit 2; }
    # extract dirname (parent path) and basename (filename)
  _sp_dirname=$(dirname "$1")
  _sp_basename=$(basename "$1")
    # determine suffix, if any
  _sp_suffix=$([[ $_sp_basename = *.* ]] && printf %s ".${_sp_basename##*.}" || printf '')
    # determine basename root (filemane w/o suffix)
  if [[ "$_sp_basename" == "$_sp_suffix" ]]; then # does filename start with '.'?
      _sp_basename_root=$_sp_basename
      _sp_suffix=''
  else # strip suffix from filename
    _sp_basename_root=${_sp_basename%$_sp_suffix}
  fi
  # assign to output vars.
  [[ -n $2 ]] && printf -v "$2" "$_sp_dirname"
  [[ -n $3 ]] && printf -v "$3" "$_sp_basename"
  [[ -n $4 ]] && printf -v "$4" "$_sp_basename_root"
  [[ -n $5 ]] && printf -v "$5" "$_sp_suffix"
  return 0
}

test_paths=(
  '/etc/bash.bashrc'
  '/usr/bin/grep'
  '/Users/jdoe/.bash_profile'
  '/Library/Application Support/'
  'readme.new.txt'
)

for p in "${test_paths[@]}"; do
  echo ----- "$p"
  parentpath= fname= fnameroot= suffix=
  splitPath "$p" parentpath fname fnameroot suffix
  for n in parentpath fname fnameroot suffix; do
    echo "$n=${!n}"
  done
done

Test code that exercises the function:

test_paths=(
  '/etc/bash.bashrc'
  '/usr/bin/grep'
  '/Users/jdoe/.bash_profile'
  '/Library/Application Support/'
  'readme.new.txt'
)

for p in "${test_paths[@]}"; do
  echo ----- "$p"
  parentpath= fname= fnameroot= suffix=
  splitPath "$p" parentpath fname fnameroot suffix
  for n in parentpath fname fnameroot suffix; do
    echo "$n=${!n}"
  done
done

Expected output - note the edge cases:

a filename having no suffix

a filename starting with . (not considered the start of the suffix)

an input path ending in / (trailing / is ignored)

an input path that is a filename only (. is returned as the parent path)

a filename that has more than .-prefixed token (only the last is considered the suffix):

----- /etc/bash.bashrc
parentpath=/etc
fname=bash.bashrc
fnameroot=bash
suffix=.bashrc
----- /usr/bin/grep
parentpath=/usr/bin
fname=grep
fnameroot=grep
suffix=
----- /Users/jdoe/.bash_profile
parentpath=/Users/jdoe
fname=.bash_profile
fnameroot=.bash_profile
suffix=
----- /Library/Application Support/
parentpath=/Library
fname=Application Support
fnameroot=Application Support
suffix=
----- readme.new.txt
parentpath=.
fname=readme.new.txt
fnameroot=readme.new
suffix=.txt

---

Here are some alternative suggestions (mostly in awk), including some advanced use cases, like extracting version numbers for software packages.

Just note that with a slightly different input some of these may fail, therefore anyone using these should validate on their expected input and adapt the regex expression if required.

f='/path/to/complex/file.1.0.1.tar.gz'

# Filename : 'file.1.0.x.tar.gz'
    echo "$f" | awk -F'/' '{print $NF}'

# Extension (last): 'gz'
    echo "$f" | awk -F'[.]' '{print $NF}'
    
# Extension (all) : '1.0.1.tar.gz'
    echo "$f" | awk '{sub(/[^.]*[.]/, "", $0)} 1'
    
# Extension (last-2): 'tar.gz'
    echo "$f" | awk -F'[.]' '{print $(NF-1)"."$NF}'

# Basename : 'file'
    echo "$f" | awk '{gsub(/.*[/]|[.].*/, "", $0)} 1'

# Basename-extended : 'file.1.0.1.tar'
    echo "$f" | awk '{gsub(/.*[/]|[.]{1}[^.]+$/, "", $0)} 1'

# Path : '/path/to/complex/'
    echo "$f" | awk '{match($0, /.*[/]/, a); print a[0]}'
    # or 
    echo "$f" | grep -Eo '.*[/]'
    
# Folder (containing the file) : 'complex'
    echo "$f" | awk -F'/' '{$1=""; print $(NF-1)}'
    
# Version : '1.0.1'
    # Defined as 'number.number' or 'number.number.number'
    echo "$f" | grep -Eo '[0-9]+[.]+[0-9]+[.]?[0-9]?'

    # Version - major : '1'
    echo "$f" | grep -Eo '[0-9]+[.]+[0-9]+[.]?[0-9]?' | cut -d. -f1

    # Version - minor : '0'
    echo "$f" | grep -Eo '[0-9]+[.]+[0-9]+[.]?[0-9]?' | cut -d. -f2

    # Version - patch : '1'
    echo "$f" | grep -Eo '[0-9]+[.]+[0-9]+[.]?[0-9]?' | cut -d. -f3

# All Components : "path to complex file 1 0 1 tar gz"
    echo "$f" | awk -F'[/.]' '{$1=""; print $0}'
    
# Is absolute : True (exit-code : 0)
    # Return true if it is an absolute path (starting with '/' or '~/'
    echo "$f" | grep -q '^[/]\|^~/'
 

All use cases are using the original full path as input, without depending on intermediate results.

---

Smallest and simplest solution (in single line) is:

$ file=/blaabla/bla/blah/foo.txt
echo $(basename ${file%.*}) # foo

---

I think that if you just need the name of the file, you can try this:

FULLPATH=/usr/share/X11/xorg.conf.d/50-synaptics.conf

# Remove all the prefix until the "/" character
FILENAME=${FULLPATH##*/}

# Remove all the prefix until the "." character
FILEEXTENSION=${FILENAME##*.}

# Remove a suffix, in our case, the filename. This will return the name of the directory that contains this file.
BASEDIRECTORY=${FULLPATH%$FILENAME}

echo "path = $FULLPATH"
echo "file name = $FILENAME"
echo "file extension = $FILEEXTENSION"
echo "base directory = $BASEDIRECTORY"

And that is all =D.

---

You can force cut to display all fields and subsequent ones adding - to field number.

NAME=`basename "$FILE"`
EXTENSION=`echo "$NAME" | cut -d'.' -f2-`

So if FILE is eth0.pcap.gz, the EXTENSION will be pcap.gz

Using the same logic, you can also fetch the file name using '-' with cut as follows :

NAME=`basename "$FILE" | cut -d'.' -f-1`

This works even for filenames that do not have any extension.

---

Magic file recognition

In addition to the lot of good answers on this Stack Overflow question I would like to add:

Under Linux and other unixen, there is a magic command named file, that do filetype detection by analysing some first bytes of file. This is a very old tool, initialy used for print servers (if not created for... I'm not sure about that).

file myfile.txt
myfile.txt: UTF-8 Unicode text

file -b --mime-type myfile.txt
text/plain

Standards extensions could be found in /etc/mime.types (on my Debian GNU/Linux desktop. See man file and man mime.types. Perhaps you have to install the file utility and mime-support packages):

grep $( file -b --mime-type myfile.txt ) </etc/mime.types
text/plain      asc txt text pot brf srt

You could create a bash function for determining right extension. There is a little (not perfect) sample:

file2ext() {
    local _mimetype=$(file -Lb --mime-type "$1") _line _basemimetype
    case ${_mimetype##*[/.-]} in
        gzip | bzip2 | xz | z )
            _mimetype=${_mimetype##*[/.-]}
            _mimetype=${_mimetype//ip}
            _basemimetype=$(file -zLb --mime-type "$1")
            ;;
        stream )
            _mimetype=($(file -Lb "$1"))
            [ "${_mimetype[1]}" = "compressed" ] &&
                _basemimetype=$(file -b --mime-type - < <(
                        ${_mimetype,,} -d <"$1")) ||
                _basemimetype=${_mimetype,,}
            _mimetype=${_mimetype,,}
            ;;
        executable )  _mimetype='' _basemimetype='' ;;
        dosexec )     _mimetype='' _basemimetype='exe' ;;
        shellscript ) _mimetype='' _basemimetype='sh' ;;
        * )
            _basemimetype=$_mimetype
            _mimetype=''
            ;;
    esac
    while read -a _line ;do
        if [ "$_line" == "$_basemimetype" ] ;then
            [ "$_line[1]" ] &&
                _basemimetype=${_line[1]} ||
                _basemimetype=${_basemimetype##*[/.-]}
            break
        fi
        done </etc/mime.types
    case ${_basemimetype##*[/.-]} in
        executable ) _basemimetype='' ;;
        shellscript ) _basemimetype='sh' ;;
        dosexec ) _basemimetype='exe' ;;
        * ) ;;
    esac
    [ "$_mimetype" ] && [ "$_basemimetype" != "$_mimetype" ] &&
      printf ${2+-v} $2 "%s.%s" ${_basemimetype##*[/.-]} ${_mimetype##*[/.-]} ||
      printf ${2+-v} $2 "%s" ${_basemimetype##*[/.-]}
}

This function could set a Bash variable that can be used later:

(This is inspired from @Petesh right answer):

filename=$(basename "$fullfile")
filename="${filename%.*}"
file2ext "$fullfile" extension

echo "$fullfile -> $filename . $extension"

---

$ F = "text file.test.txt"  
$ echo ${F/*./}  
txt  

This caters for multiple dots and spaces in a filename, however if there is no extension it returns the filename itself. Easy to check for though; just test for the filename and extension being the same.

Naturally this method doesn't work for .tar.gz files. However that could be handled in a two step process. If the extension is gz then check again to see if there is also a tar extension.

---

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 =)

---

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%.*};

---

This is the only one that worked for me:

path='folder/other_folder/file.js'

base=${path##*/}
echo ${base%.*}

>> file

This can also be used in string interpolation as well, but unfortunately you have to set base beforehand.

---

I use the following script

$ echo "foo.tar.gz"|rev|cut -d"." -f3-|rev
foo

---

How to extract the filename and extension in fish:

function split-filename-extension --description "Prints the filename and extension"
  for file in $argv
    if test -f $file
      set --local extension (echo $file | awk -F. '{print $NF}')
      set --local filename (basename $file .$extension)
      echo "$filename $extension"
    else
      echo "$file is not a valid file"
    end
  end
end

Caveats: Splits on the last dot, which works well for filenames with dots in them, but not well for extensions with dots in them. See example below.

Usage:

$ split-filename-extension foo-0.4.2.zip bar.tar.gz
foo-0.4.2 zip  # Looks good!
bar.tar gz  # Careful, you probably want .tar.gz as the extension.

There's probably better ways to do this. Feel free to edit my answer to improve it.

If there's a limited set of extensions you'll be dealing with and you know all of them, try this:

switch $file
  case *.tar
    echo (basename $file .tar) tar
  case *.tar.bz2
    echo (basename $file .tar.bz2) tar.bz2
  case *.tar.gz
    echo (basename $file .tar.gz) tar.gz
  # and so on
end

This does not have the caveat as the first example, but you do have to handle every case so it could be more tedious depending on how many extensions you can expect.

---

Here is code with AWK. It can be done more simply. But I am not good in AWK.

filename$ ls
abc.a.txt  a.b.c.txt  pp-kk.txt
filename$ find . -type f | awk -F/ '{print $2}' | rev | awk -F"." '{$1="";print}' | rev | awk 'gsub(" ",".") ,sub(".$", "")'
abc.a
a.b.c
pp-kk
filename$ find . -type f | awk -F/ '{print $2}' | awk -F"." '{print $NF}'
txt
txt
txt

---

No previous answer used a bash regex Here's a pure bash solution that splits a path into:

The directory path, with its trailing / when present The regex that discards the trailing / is so much longer that I didn't post it

The filename, excluding the (last) dot extension

The (last) dot extension, with its leading .

The code is meant to handle every possible case, you're welcome to try it.

#!/bin/bash

for path; do

####### the relevant part ######

[[ $path =~ ^(\.{1,2}|.*/\.{0,2})$|^(.*/)([^/]+)(\.[^/]*)$|^(.*/)(.+)$|^(.+)(\..*)$|^(.+)$ ]]

dirpath=${BASH_REMATCH[1]}${BASH_REMATCH[2]}${BASH_REMATCH[5]}
filename=${BASH_REMATCH[3]}${BASH_REMATCH[6]}${BASH_REMATCH[7]}${BASH_REMATCH[9]}
filext=${BASH_REMATCH[4]}${BASH_REMATCH[8]}

# dirpath should be non-null
[[ $dirpath ]] || dirpath='.'

################################

printf '%s=%q\n' \
    path     "$path" \
    dirpath  "$dirpath" \
    filename "$filename" \
    filext   "$filext"

done

How does it work?

Basically, it ensures that only one sub-expression (delimited with | in the regex) is able to capture the input. Thanks to that, you can concatenate all the capture groups of the same type (for example, the ones related to the directory path) stored in BASH_REMATCH, because at most one will be non-null.

Here are the results of an extended but not exhaustive set of examples:

+--------------------------------------------------------+
| input             dirpath        filename       filext |
+--------------------------------------------------------+
''                  .              ''             ''
.                   .              ''             ''
..                  ..             ''             ''
...                 .              ..             .
.file               .              .file          ''
.file.              .              .file          .
.file..             .              .file.         .
.file.Z             .              .file          .Z
.file.sh.Z          .              .file.sh       .Z
file                .              file           ''
file.               .              file           .
file..              .              file.          .
file.Z              .              file           .Z
file.sh.Z           .              file.sh        .Z
dir/                dir/           ''             ''
dir/.               dir/.          ''             ''
dir/...             dir/           ..             .
dir/.file           dir/           .file          ''
dir/.file.          dir/           .file          .
dir/.file..         dir/           .file.         .
dir/.file.Z         dir/           .file          .Z
dir/.file.x.Z       dir/           .file.x        .Z
dir/file            dir/           file           ''
dir/file.           dir/           file           .
dir/file..          dir/           file.          .
dir/file.Z          dir/           file           .Z
dir/file.x.Z        dir/           file.x         .Z
dir./.              dir./.         ''             ''
dir./...            dir./          ..             .
dir./.file          dir./          .file          ''
dir./.file.         dir./          .file          .
dir./.file..        dir./          .file.         .
dir./.file.Z        dir./          .file          .Z
dir./.file.sh.Z     dir./          .file.sh       .Z
dir./file           dir./          file           ''
dir./file.          dir./          file           .
dir./file..         dir./          file.          .
dir./file.Z         dir./          file           .Z
dir./file.x.Z       dir./          file.x         .Z
dir//               dir//          ''             ''
dir//.              dir//.         ''             ''
dir//...            dir//          ..             .
dir//.file          dir//          .file          ''
dir//.file.         dir//          .file          .
dir//.file..        dir//          .file.         .
dir//.file.Z        dir//          .file          .Z
dir//.file.x.Z      dir//          .file.x        .Z
dir//file           dir//          file           ''
dir//file.          dir//          file           .
dir//file..         dir//          file.          .
dir//file.Z         dir//          file           .Z
dir//file.x.Z       dir//          file.x         .Z
dir.//.             dir.//.        ''             ''
dir.//...           dir.//         ..             .
dir.//.file         dir.//         .file          ''
dir.//.file.        dir.//         .file          .
dir.//.file..       dir.//         .file.         .
dir.//.file.Z       dir.//         .file          .Z
dir.//.file.x.Z     dir.//         .file.x        .Z
dir.//file          dir.//         file           ''
dir.//file.         dir.//         file           .
dir.//file..        dir.//         file.          .
dir.//file.Z        dir.//         file           .Z
dir.//file.x.Z      dir.//         file.x         .Z
/                   /              ''             ''
/.                  /.             ''             ''
/..                 /..            ''             ''
/...                /              ..             .
/.file              /              .file          ''
/.file.             /              .file          .
/.file..            /              .file.         .
/.file.Z            /              .file          .Z
/.file.sh.Z         /              .file.sh       .Z
/file               /              file           ''
/file.              /              file           .
/file..             /              file.          .
/file.Z             /              file           .Z
/file.sh.Z          /              file.sh        .Z
/dir/               /dir/          ''             ''
/dir/.              /dir/.         ''             ''
/dir/...            /dir/          ..             .
/dir/.file          /dir/          .file          ''
/dir/.file.         /dir/          .file          .
/dir/.file..        /dir/          .file.         .
/dir/.file.Z        /dir/          .file          .Z
/dir/.file.x.Z      /dir/          .file.x        .Z
/dir/file           /dir/          file           ''
/dir/file.          /dir/          file           .
/dir/file..         /dir/          file.          .
/dir/file.Z         /dir/          file           .Z
/dir/file.x.Z       /dir/          file.x         .Z
/dir./.             /dir./.        ''             ''
/dir./...           /dir./         ..             .
/dir./.file         /dir./         .file          ''
/dir./.file.        /dir./         .file          .
/dir./.file..       /dir./         .file.         .
/dir./.file.Z       /dir./         .file          .Z
/dir./.file.sh.Z    /dir./         .file.sh       .Z
/dir./file          /dir./         file           ''
/dir./file.         /dir./         file           .
/dir./file..        /dir./         file.          .
/dir./file.Z        /dir./         file           .Z
/dir./file.x.Z      /dir./         file.x         .Z
/dir//              /dir//         ''             ''
/dir//.             /dir//.        ''             ''
/dir//...           /dir//         ..             .
/dir//.file         /dir//         .file          ''
/dir//.file.        /dir//         .file          .
/dir//.file..       /dir//         .file.         .
/dir//.file.Z       /dir//         .file          .Z
/dir//.file.x.Z     /dir//         .file.x        .Z
/dir//file          /dir//         file           ''
/dir//file.         /dir//         file           .
/dir//file..        /dir//         file.          .
/dir//file.Z        /dir//         file           .Z
/dir//file.x.Z      /dir//         file.x         .Z
/dir.//.            /dir.//.       ''             ''
/dir.//...          /dir.//        ..             .
/dir.//.file        /dir.//        .file          ''
/dir.//.file.       /dir.//        .file          .
/dir.//.file..      /dir.//        .file.         .
/dir.//.file.Z      /dir.//        .file          .Z
/dir.//.file.x.Z    /dir.//        .file.x        .Z
/dir.//file         /dir.//        file           ''
/dir.//file.        /dir.//        file           .
/dir.//file..       /dir.//        file.          .
/dir.//file.Z       /dir.//        file           .Z
/dir.//file.x.Z     /dir.//        file.x         .Z
//                  //             ''             ''
//.                 //.            ''             ''
//..                //..           ''             ''
//...               //             ..             .
//.file             //             .file          ''
//.file.            //             .file          .
//.file..           //             .file.         .
//.file.Z           //             .file          .Z
//.file.sh.Z        //             .file.sh       .Z
//file              //             file           ''
//file.             //             file           .
//file..            //             file.          .
//file.Z            //             file           .Z
//file.sh.Z         //             file.sh        .Z
//dir/              //dir/         ''             ''
//dir/.             //dir/.        ''             ''
//dir/...           //dir/         ..             .
//dir/.file         //dir/         .file          ''
//dir/.file.        //dir/         .file          .
//dir/.file..       //dir/         .file.         .
//dir/.file.Z       //dir/         .file          .Z
//dir/.file.x.Z     //dir/         .file.x        .Z
//dir/file          //dir/         file           ''
//dir/file.         //dir/         file           .
//dir/file..        //dir/         file.          .
//dir/file.Z        //dir/         file           .Z
//dir/file.x.Z      //dir/         file.x         .Z
//dir./.            //dir./.       ''             ''
//dir./...          //dir./        ..             .
//dir./.file        //dir./        .file          ''
//dir./.file.       //dir./        .file          .
//dir./.file..      //dir./        .file.         .
//dir./.file.Z      //dir./        .file          .Z
//dir./.file.sh.Z   //dir./        .file.sh       .Z
//dir./file         //dir./        file           ''
//dir./file.        //dir./        file           .
//dir./file..       //dir./        file.          .
//dir./file.Z       //dir./        file           .Z
//dir./file.x.Z     //dir./        file.x         .Z
//dir//             //dir//        ''             ''
//dir//.            //dir//.       ''             ''
//dir//...          //dir//        ..             .
//dir//.file        //dir//        .file          ''
//dir//.file.       //dir//        .file          .
//dir//.file..      //dir//        .file.         .
//dir//.file.Z      //dir//        .file          .Z
//dir//.file.x.Z    //dir//        .file.x        .Z
//dir//file         //dir//        file           ''
//dir//file.        //dir//        file           .
//dir//file..       //dir//        file.          .
//dir//file.Z       //dir//        file           .Z
//dir//file.x.Z     //dir//        file.x         .Z
//dir.//.           //dir.//.      ''             ''
//dir.//...         //dir.//       ..             .
//dir.//.file       //dir.//       .file          ''
//dir.//.file.      //dir.//       .file          .
//dir.//.file..     //dir.//       .file.         .
//dir.//.file.Z     //dir.//       .file          .Z
//dir.//.file.x.Z   //dir.//       .file.x        .Z
//dir.//file        //dir.//       file           ''
//dir.//file.       //dir.//       file           .
//dir.//file..      //dir.//       file.          .
//dir.//file.Z      //dir.//       file           .Z
//dir.//file.x.Z    //dir.//       file.x         .Z

As you can see, the behaviour is different from basename and dirname. For example basename dir/ outputs dir while the regex will give you an empty filename for it. Same for . and .., those are considered directories, not filenames.

I timed it with 10000 paths of 256 characters and it took about 1 second, while the equivalent POSIX shell solution is 2x slower and solutions based on wild forking (external calls inside the for loop) are at least 60x slower.

remark: It's not necessary to test paths that contain \n or other notorious characters because all characters are handled the same way by the regex engine of bash. The only characters that would be able to break the current logic are / and ., intermixed or multiplied in a currently unexpected way. When I first posted my answer I found a few border cases that I had to fix; I can't say that the regex is 100% bullet proof but it should be quite robust now.

As an aside, here's the POSIX shell solution that yields the same output:

#!/bin/sh

for path; do

####### the relevant part ######

fullname=${path##*/}

case $fullname in
. | ..)
    dirpath="$path"
    filename=''
    filext=''
    ;;
*)
    dirpath=${path%"$fullname"}
    dirpath=${dirpath:-.}       # dirpath should be non-null
    filename=${fullname#.}
    filename="${fullname%"$filename"}${filename%.*}"
    filext=${fullname#"$filename"}
    ;;
esac

################################

printf '%s=%s\n' \
    path     "$path" \
    dirpath  "$dirpath" \
    filename "$filename" \
    filext   "$filext"

done

postscript: There are a few points for which some people might disagree with the results given by the above codes:

The special case of dotfiles: The reason is that dotfiles are a UNIX concept.

The special case of . and ..: IMHO it seems obvious to treat them as directories, but most libraries don't do that and force the user to post-process the result.

No support for double-extensions: That's because you'd need a whole database for storing all the valid double-extensions, and above all, because file extensions don't mean anything in UNIX; for example you can call a tar archive my_tarred_files and that's completely fine, you'll be able to tar xf my_tarred_files without any problem.

---

Building from Petesh answer, if only the filename is needed, both path and extension can be stripped in a single line,

filename=$(basename ${fullname%.*})

---

Based largely off of @mklement0's excellent, and chock-full of random, useful bashisms - as well as other answers to this / other questions / "that darn internet"... I wrapped it all up in a little, slightly more comprehensible, reusable function for my (or your) .bash_profile that takes care of what (I consider) should be a more robust version of dirname/basename / what have you..

function path { SAVEIFS=$IFS; IFS=""   # stash IFS for safe-keeping, etc.
    [[ $# != 2 ]] && echo "usage: path <path> <dir|name|fullname|ext>" && return    # demand 2 arguments
    [[ $1 =~ ^(.*/)?(.+)?$ ]] && {     # regex parse the path
        dir=${BASH_REMATCH[1]}
        file=${BASH_REMATCH[2]}
        ext=$([[ $file = *.* ]] && printf %s ${file##*.} || printf '')
        # edge cases for extensionless files and files like ".nesh_profile.coffee"
        [[ $file == $ext ]] && fnr=$file && ext='' || fnr=${file:0:$((${#file}-${#ext}))}
        case "$2" in
             dir) echo      "${dir%/*}"; ;;
            name) echo      "${fnr%.*}"; ;;
        fullname) echo "${fnr%.*}.$ext"; ;;
             ext) echo           "$ext"; ;;
        esac
    }
    IFS=$SAVEIFS
}     

Usage examples...

SOMEPATH=/path/to.some/.random\ file.gzip
path $SOMEPATH dir        # /path/to.some
path $SOMEPATH name       # .random file
path $SOMEPATH ext        # gzip
path $SOMEPATH fullname   # .random file.gzip                     
path gobbledygook         # usage: -bash <path> <dir|name|fullname|ext>

---

A simple answer:

To expand on the POSIX variables answer, note that you can do more interesting patterns. So for the case detailed here, you could simply do this:

tar -zxvf $1
cd ${1%.tar.*}

That will cut off the last occurrence of .tar..

More generally, if you wanted to remove the last occurrence of .. then

${1.*.*}

should work fine.

The link the above answer appears to be dead. Here's a great explanation of a bunch of the string manipulation you can do directly in Bash, from TLDP.

---

If you also want to allow empty extensions, this is the shortest I could come up with:

echo 'hello.txt' | sed -r 's/.+\.(.+)|.*/\1/' # EXTENSION
echo 'hello.txt' | sed -r 's/(.+)\..+|(.*)/\1\2/' # FILENAME

1st line explained: It matches PATH.EXT or ANYTHING and replaces it with EXT. If ANYTHING was matched, the ext group is not captured.

---

IMHO the best solution has already been given (using shell parameter expansion) and are the best rated one at this time.

I however add this one which just use dumbs commands, which is not efficient and which noone serious should use ever :

FILENAME=$(echo $FILE | cut -d . -f 1-$(printf $FILE | tr . '\n' | wc -l))
EXTENSION=$(echo $FILE | tr . '\n' | tail -1)

Added just for fun :-)

---

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

---