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.
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"
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 $FILE is not a symlink
fi
first you can do with this style:
mda="/usr/mda"
if [ ! -L "${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
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.
-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
Is the file really a symbolic link? If not, the usual test for existence is -r
or -e
.
See man test
.
If you are testing for file existence you want -e not -L. -L tests for a symlink.
Source: Stackoverflow.com