Given an absolute or relative path (in a Unix-like system), I would like to determine the full path of the target after resolving any intermediate symlinks. Bonus points for
Here I present what I believe to be a cross-platform (Linux and macOS at least) solution to the answer that is working well for me currently.
crosspath()
{
local ref="$1"
if [ -x "$(which realpath)" ]; then
path="$(realpath "$ref")"
else
path="$(readlink -f "$ref" 2> /dev/null)"
if [ $? -gt 0 ]; then
if [ -x "$(which readlink)" ]; then
if [ ! -z "$(readlink "$ref")" ]; then
ref="$(readlink "$ref")"
fi
else
echo "realpath and readlink not available. The following may not be the final path." 1>&2
fi
if [ -d "$ref" ]; then
path="$(cd "$ref"; pwd -P)"
else
path="$(cd $(dirname "$ref"); pwd -P)/$(basename "$ref")"
fi
fi
fi
echo "$path"
}
Here is a macOS (only?) solution. Possibly better suited to the original question.
mac_realpath()
{
local ref="$1"
if [[ ! -z "$(readlink "$ref")" ]]; then
ref="$(readlink "$1")"
fi
if [[ -d "$ref" ]]; then
echo "$(cd "$ref"; pwd -P)"
else
echo "$(cd $(dirname "$ref"); pwd -P)/$(basename "$ref")"
fi
}
This is a symlink resolver in Bash that works whether the link is a directory or a non-directory:
function readlinks {(
set -o errexit -o nounset
declare n=0 limit=1024 link="$1"
# If it's a directory, just skip all this.
if cd "$link" 2>/dev/null
then
pwd -P
return 0
fi
# Resolve until we are out of links (or recurse too deep).
while [[ -L $link ]] && [[ $n -lt $limit ]]
do
cd "$(dirname -- "$link")"
n=$((n + 1))
link="$(readlink -- "${link##*/}")"
done
cd "$(dirname -- "$link")"
if [[ $n -ge $limit ]]
then
echo "Recursion limit ($limit) exceeded." >&2
return 2
fi
printf '%s/%s\n' "$(pwd -P)" "${link##*/}"
)}
Note that all the cd
and set
stuff takes place in a subshell.
My answer here Bash: how to get real path of a symlink?
but in short very handy in scripts:
script_home=$( dirname $(realpath "$0") )
echo Original script home: $script_home
These are part of GNU coreutils, suitable for use in Linux systems.
To test everything, we put symlink into /home/test2/, amend some additional things and run/call it from root directory:
/$ /home/test2/symlink
/home/test
Original script home: /home/test
Where
Original script is: /home/test/realscript.sh
Called script is: /home/test2/symlink
Another way:
# Gets the real path of a link, following all links
myreadlink() { [ ! -h "$1" ] && echo "$1" || (local link="$(expr "$(command ls -ld -- "$1")" : '.*-> \(.*\)$')"; cd $(dirname $1); myreadlink "$link" | sed "s|^\([^/].*\)\$|$(dirname $1)/\1|"); }
# Returns the absolute path to a command, maybe in $PATH (which) or not. If not found, returns the same
whereis() { echo $1 | sed "s|^\([^/].*/.*\)|$(pwd)/\1|;s|^\([^/]*\)$|$(which -- $1)|;s|^$|$1|"; }
# Returns the realpath of a called command.
whereis_realpath() { local SCRIPT_PATH=$(whereis $1); myreadlink ${SCRIPT_PATH} | sed "s|^\([^/].*\)\$|$(dirname ${SCRIPT_PATH})/\1|"; }
Here's how one can get the actual path to the file in MacOS/Unix using an inline Perl script:
FILE=$(perl -e "use Cwd qw(abs_path); print abs_path('$0')")
Similarly, to get the directory of a symlinked file:
DIR=$(perl -e "use Cwd qw(abs_path); use File::Basename; print dirname(abs_path('$0'))")
function realpath {
local r=$1; local t=$(readlink $r)
while [ $t ]; do
r=$(cd $(dirname $r) && cd $(dirname $t) && pwd -P)/$(basename $t)
t=$(readlink $r)
done
echo $r
}
#example usage
SCRIPT_PARENT_DIR=$(dirname $(realpath "$0"))/..