How can I detect whether a symlink is broken in Bash?

Question

I run find and iterate through the results with [ $ -L $F $ ] to collect certain symbolic links.

I am wondering if there is an easy way to determine if the link is broken (points to a non-existent file) in this scenario.

Here is my code:

FILES=`find /target/ | grep -v '\.disabled$' | sort`

for F in $FILES; do
    if [ -L $F ]; then
        DO THINGS
    fi
done

score 61 · Accepted Answer · edited Nov 27 '19 at 15:17

61

# test if symlink is broken (by seeing if it links to an existing file)
if [ ! -e "$F" ] ; then
    # code if the symlink is broken
fi

edited Nov 27 '19 at 15:17

Ross Smith II

11,799
1
38
43

answered Nov 08 '11 at 10:45

Roger

690
6
2

5

Note that the code will also be executed if the file does not exist at all. It is fine with `find` but in other scenarios (such as globs) should be combined with -h to handle this case, for instance `[ -h "$F" -a ! -e "$F" ]`. – Calimo Apr 18 '17 at 19:50
2

You're not really testing the symbolic link with this approach. – Sridhar Sarnobat Jul 13 '17 at 22:36
@Calimo There is no difference. – Melab Jul 24 '17 at 15:22
6

@Melab wrong... Please test your assumptions before commenting: https://git.io/fx95w This answer is INCORRECT. – hasufell Oct 27 '18 at 07:04
Didn't work for me. I created a link, then I removed the target file and the check was still returning true – cisk Jan 10 '20 at 10:10
@Camilo solution worked for me in a more general case (not with find) – mikemtnbikes Jan 12 '21 at 22:04
FYI all: see `man test` or `man [` for the information on what `-e` means. Note that in bash, `[` itself is a command. Therefore, `!` is the first arg to it, `-e` is the 2nd arg to it, `"$F"` is the 3rd arg, `]` is the 4th arg. That's why spaces are required after the `[` and before the `]`--the first is the command name and the latter is a required argument, and commands and arguments must always be separated by spaces. – Gabriel Staples Mar 14 '21 at 08:45

Shawn Chin · Answer 2 · 2011-11-08T11:30:45.680

38

This should print out links that are broken:

find /target/dir -type l ! -exec test -e {} \; -print

You can also chain in operations to find command, e.g. deleting the broken link:

find /target/dir -type l ! -exec test -e {} \; -exec rm {} \;

edited Nov 08 '11 at 11:30

answered Nov 08 '11 at 10:51

Shawn Chin

84,080
19
162
191

This doesn't work well if you are actually running lots of code. Do you have a `if` solution ? – Freedo Aug 30 '19 at 17:50

score 11 · Answer 3 · answered May 04 '14 at 23:46

11

this will work if the symlink was pointing to a file or a directory, but now is broken

if [[ -L "$strFile" ]] && [[ ! -a "$strFile" ]];then 
  echo "'$strFile' is a broken symlink"; 
fi

answered May 04 '14 at 23:46

Aquarius Power

3,729
5
32
67

wouldn't the `-L "$strFile"` suffice? From the docs: `[-L FILE ] True if FILE exists and is a symbolic link.` ([source](http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_01.html). – Sos Jul 22 '19 at 08:12
1

@Sosi could this be required in an old bash version? 2014 vs 2019, I could even dont have that version anymore :) – Aquarius Power Jul 22 '19 at 19:08
right! that's a great point! I didn't notice how old this was, and now I feel bad for digging it up – Sos Jul 23 '19 at 07:02
@Sosi I think there is no problem, an updated app version's answer is always better I guess – Aquarius Power Jul 23 '19 at 17:02
3

@Sosi We want to test if the symbolic link is working, -L is true even if the file is just a broken symlink – Freedo Aug 30 '19 at 17:51

score 4 · Answer 4 · answered May 24 '14 at 13:02

4

This finds all files of type "link", which also resolves to a type "link". ie. a broken symlink

find /target -type l -xtype l

answered May 24 '14 at 13:02

ACyclic

5,904
6
26
28

2

variant: `find -L /target -type l` – cdelacroix Jun 23 '15 at 12:59
Can't you have a symlink to a symlink that isn't broken?' – Sridhar Sarnobat Jul 13 '17 at 22:38
GNU `find` and `-xtype` resolves the symlink all the way to the end. If a symlink is good it will always resolve to something that is not a symlink. Same with `-L` in GNU `find` and BSD `find`. – docwhat Jun 27 '22 at 16:25

score 2 · Answer 5 · edited Jun 24 '15 at 14:22

2

If you don't mind traversing non-broken dir symlinks, to find all orphaned links:

$ find -L /target -type l | while read -r file; do echo $file is orphaned; done

To find all files that are not orphaned links:

$ find -L /target ! -type l

edited Jun 24 '15 at 14:22

ACyclic

5,904
6
26
28

answered Nov 08 '11 at 10:55

William Pursell

204,365
48
270
300

1

But this follows non-broken symlinks to directories, which we may not want. – rafak Dec 15 '12 at 13:01
`/target` could be a file in which case directory traversal isn't a problem. – docwhat Jun 27 '22 at 16:28

score -1 · Answer 6 · answered May 31 '19 at 15:54

-1

What's wrong with:

file $f | grep 'broken symbolic link'

answered May 31 '19 at 15:54

Rew Brian

23
5

3

There's a few things wrong with it: 1) it follows a working symbolic link and, if the target is a file, will read the contents to try to determine its type; 2) how the output is worded may not be the same everywhere and forever; 3) if the system it's run on is in a locale other than English, it may not print the English message. Add `-h` flag to fix the first problem, and prefix it with `LANG=C` to fix the third. You may or may not consider the second problem an acceptable risk. – kbolino Jul 10 '19 at 22:33

score -1 · Answer 7 · answered Aug 17 '20 at 14:08

-1

If it does qualify as a symbolic link, but is „not existing“, its a broken link.

if [[ -h $link && ! -e $link ]] ; then
    _info "$link is a BROKEN SYMLINK"
fi

REFERENCE

answered Aug 17 '20 at 14:08

Frank N

9,625
4
80
110

`-h` is described as *True if file exists and is a symbolic link.* If `-h` is true then `-e` is true. – docwhat Jun 27 '22 at 16:27

How can I detect whether a symlink is broken in Bash?

7 Answers7

Linked

Related