How to check if a symlink exists

Question

I'm trying to check if a symlink exists in bash. Here's what I've tried.

mda=/usr/mda
if [ ! -L $mda ]; then
  echo "=> File doesn't exist"
fi


mda='/usr/mda'
if [ ! -L $mda ]; then
  echo "=> File doesn't exist"
fi

However, that doesn't work. If '!' is left out, it never triggers. And if '!' is there, it triggers every time.

for what its worth, if you use [[ ! -D $mda ]] works just fine.. — DMin, Dec 13 '17 at 06:55

score 416 · Accepted Answer · edited May 30 '17 at 18:30

416

-L returns true if the "file" exists and is a symbolic link (the linked file may or may not exist). You want -f (returns true if file exists and is a regular file) or maybe just -e (returns true if file exists regardless of type).

According to the GNU manpage, -h is identical to -L, but according to the BSD manpage, it should not be used:

-h file True if file exists and is a symbolic link. This operator is retained for compatibility with previous versions of this program. Do not rely on its existence; use -L instead.

edited May 30 '17 at 18:30

Soviut

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answered Apr 23 '11 at 21:31

drysdam

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I'm looking to see if a symlink DOESN'T exist. !-h or !-L should work for symlinks, !-e should work otherwise. – bear Apr 23 '11 at 21:32
57

To help anyone who finds this via Google as I did, the full syntax using `!` is `if ! [ -L $mda ]; then .... fi` i.e. put the exclamation mark _outside_ the square brackets. – Sam Sep 05 '12 at 08:06
30

Just wanted to add a little something to the tip given by @Sam; when doing these sorts of operations make sure to put your file name in quotes, to prevent issues with whitespaces. e.g. `if [ ! -L "$mda" ]; then ... fi` (note: `if [ ! ... ]` and `if ! [ ... ]` are identical :) – Thomas Vervest Aug 06 '13 at 12:26
2

do you really see a difference between -L and -h ? in my bash ( version 4.2.53(1)-release (x86_64-redhat-linux-gnu ) man bash is identical for both -L and -h and they behave the same, ie they check that file actualy is a link and don't care whether the linked to file exists or not. – philippe lhardy Jan 19 '15 at 14:41
4

Yes, `-L` and `-h` are the [same](https://stackoverflow.com/questions/1997666/difference-between-test-h-and-test-l). `man test` also confirms this. – Sparhawk Feb 09 '15 at 01:20
1

Anybody has an idea how to check whether the **target file** exists? – Tomáš Zato Apr 21 '15 at 17:10
@Sparhawk - any idea why they might be synonymous in the first place? The best reason my googling came up with is "because it's bash" – aaaaaa May 29 '15 at 07:10
2

@aaaaaa No idea… I thought I remembered some commands where `-h` was to do with symlinks, but I can't seem to find them now. `cp -H` is similar I guess, although mostly `-h` is to show the help. You should ask it as a question (perhaps in Unix/Linux)! – Sparhawk May 29 '15 at 12:41
1

@aaaaaa `man test` on BSD's `test` provided some insight about `-h`: `This operator is retained for compatibility with previous versions of this program. Do not rely on its existence; use -L instead.` As for why they changed to `-L` over `-h`, I have no idea – SnoringFrog Jan 14 '16 at 20:25
1

@TomášZato `-e $(readlink -f $symlink)` would check if the linked file exists, but has the caveat that is also return true if `$symlink` exists but is not actually a symlink. – SnoringFrog Jan 14 '16 at 20:41
2

it seems if a link is broken, -e doesn't work but only -L can tell if the link exist (though the linked file doesn't exist). Is there anyway to test if a file/or even broken link exist ? – dragonxlwang Feb 28 '16 at 20:31
2

-f also return true if the file is a symbolic link and target is exist. – jolestar Aug 02 '17 at 02:54
1

@dragonxlwang Just ran into a super annoying bug because of this. This detail should probably be added to the answer to help others in the future. – Jon Anderson Apr 02 '18 at 23:19

score 99 · Answer 2 · edited Jan 24 '21 at 14:37

99

You can check the existence of a symlink and that it is not broken with:

[ -L ${my_link} ] && [ -e ${my_link} ]

So, the complete solution is:

if [ -L ${my_link} ] ; then
   if [ -e ${my_link} ] ; then
      echo "Good link"
   else
      echo "Broken link"
   fi
elif [ -e ${my_link} ] ; then
   echo "Not a link"
else
   echo "Missing"
fi

-L tests whether there is a symlink, broken or not. By combining with -e you can test whether the link is valid (links to a directory or file), not just whether it exists.

edited Jan 24 '21 at 14:37

Sinjai

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answered Mar 23 '16 at 13:48

Chen Levy

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4

-L test if there is a symlink, broken or not. By combining with -e it is possible to test if the link is also valid (linking to a directory or file). Up-voting this solutions, since I find it important to capture this aspect. – Torbjörn Österdahl Mar 03 '20 at 09:11
Thanks ! I'm struggling with the logic behind if, this post really helped me ! +1 – Liso Oct 05 '21 at 06:47
bash friendly: `if [[ -L "${my_link}" ]]; then` ... – Jesse Nickles Aug 02 '22 at 10:14

score 40 · Answer 3 · answered Apr 23 '11 at 21:38

40

-L is the test for file exists and is also a symbolic link

If you do not want to test for the file being a symbolic link, but just test to see if it exists regardless of type (file, directory, socket etc) then use -e

So if file is really file and not just a symbolic link you can do all these tests and get an exit status whose value indicates the error condition.

if [ ! \( -e "${file}" \) ]
then
     echo "%ERROR: file ${file} does not exist!" >&2
     exit 1
elif [ ! \( -f "${file}" \) ]
then
     echo "%ERROR: ${file} is not a file!" >&2
     exit 2
elif [ ! \( -r "${file}" \) ]
then
     echo "%ERROR: file ${file} is not readable!" >&2
     exit 3
elif [ ! \( -s "${file}" \) ]
then
     echo "%ERROR: file ${file} is empty!" >&2
     exit 4
fi

answered Apr 23 '11 at 21:38

Corin

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16

`-e "${file}"` fails if the symlink exists but its target does not exist. – Flimm May 31 '12 at 11:17
2

Same result as Flimm. I'm on OS X. For me, -L and -h work for symlinks, but not -e or -f. – pauljm Apr 14 '14 at 20:43
3

@Flimm, so if I just want to test if a filename is taken (whether it's a file or symlink without target existing) what's the best way to do it? apparently -e doesn't work – dragonxlwang Feb 28 '16 at 20:34
@dragonxlwang maybe `[ -L $file_or_link ] || [ -e $file_or_link ]`? – Aurelia Peters May 19 '22 at 15:24

score 18 · Answer 4 · edited Apr 04 '12 at 17:25

18

Maybe this is what you are looking for. To check if a file exist and is not a link.

Try this command:

file="/usr/mda" 
[ -f $file ] && [ ! -L $file ] && echo "$file exists and is not a symlink"

edited Apr 04 '12 at 17:25

Eliot Sykes

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answered Apr 23 '11 at 21:31

Lynch

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popedotninja · Answer 5 · 2017-01-06T03:13:58.880

13

How about using readlink?

# if symlink, readlink returns not empty string (the symlink target)
# if string is not empty, test exits w/ 0 (normal)
#
# if non symlink, readlink returns empty string
# if string is empty, test exits w/ 1 (error)
simlink? () {
  test "$(readlink "${1}")";
}

FILE=/usr/mda

if simlink? "${FILE}"; then
  echo $FILE is a symlink
else
  echo $FILE is not a symlink
fi

edited Jan 06 '17 at 03:13

answered Jan 06 '17 at 03:04

popedotninja

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Amin Shateri · Answer 6 · 2018-09-17T16:04:12.743

5

first you can do with this style:

mda="/usr/mda"
if [ ! -L "${mda}" ]; then
  echo "=> File doesn't exist"
fi

if you want to do it in more advanced style you can write it like below:

#!/bin/bash
mda="$1"
if [ -e "$1" ]; then
    if [ ! -L "$1" ]
    then
        echo "you entry is not symlink"
    else
        echo "your entry is symlink"
    fi
else
  echo "=> File doesn't exist"
fi

the result of above is like:

root@linux:~# ./sym.sh /etc/passwd
you entry is not symlink
root@linux:~# ./sym.sh /usr/mda 
your entry is symlink
root@linux:~# ./sym.sh 
=> File doesn't exist

edited Sep 17 '18 at 16:04

answered Sep 17 '18 at 15:09

Amin Shateri

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The first invocation is wrong if the file exists but is not a link, or is a dangling link. The second is wrong if the path is a dangling symlink. – Jonathan Klabunde Tomer Jan 10 '19 at 22:29

score 5 · Answer 7 · answered Apr 23 '11 at 21:31

5

Is the file really a symbolic link? If not, the usual test for existence is -r or -e.

See man test.

answered Apr 23 '11 at 21:31

DigitalRoss

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score 4 · Answer 8 · answered Apr 23 '11 at 21:30

4

If you are testing for file existence you want -e not -L. -L tests for a symlink.

answered Apr 23 '11 at 21:30

Andrew Lazarus

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I'm looking to see if a symlink DOESN'T exist. !-h or !-L should work for symlinks, !-e should work otherwise. – bear Apr 23 '11 at 21:32
3

What you want is not clear. The file exists and is not a symlink? Then test *both* -e and !-h . – Andrew Lazarus Apr 23 '11 at 21:40

How to check if a symlink exists

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