Related
The issue that I have is with the line: "does not work" - below. The last line does indeed work - but I need to understand why the second to last line does not. I need to check for file existence on the remote server.
Have a need to check for existence for files at the following location:
/home/remoteuser/files/
and when the files are processed, they are moved to:
/home/remoteuser/logs/archive/
Would like to create an alert if the files exist at - in other words, the files were not processed:
/home/remoteuser/logs/
Found the following page and seems to be what I am looking for:
http://www.cyberciti.biz/tips/find-out-if-file-exists-with-conditional-expressions.html
Testing this and I know there are files there, but does not work:
ssh remoteuser#1.2.3.4 [ ! -f /home/remoteuser/logs/archive/*.* ] && echo "File does not exist in the root" >> /home/localuser/files/dirlist.txt
Because we know this works and does indeed list files on the local server:
ssh remoteuser#1.2.3.4 ls -l /home/remoteuser/logs/archive/*.* >> /home/localuser/files/dirlist.txt
Wildcards and test construct in Bash
You cannot use the wildcards in the [ command to test the existence of multiple files. In fact, the wildcards will be expanded and all the files will be passed to the test. Te results is that it would complain that "-f" is given too many arguments.
Try this in any non empty directory to see the output:
[ ! -f *.* ]
The only situation in which the above command does not fail is when there is only one file matching the expression, in your case a non hidden file of the form "*.*" in /home/remoteuser/logs/archive/
Using Find
A possible solution is to use find in combination with grep:
ssh name#server find /path/to/the/files -type f -name "\*.\*" 2>/dev/null | grep -q . && echo "Not Empty" || echo "Empty"
find search for regular files (-type f) whose names are in the form . (-name) and return false if nothing is found, then "grep -q ." return 1 or 0 if something is found or not.
Your goal can be accomplished with only shell builtins -- and without any uses of those builtins which depend on their behavior when passed invalid syntax (as the [ ! -e *.* ] approach does). This removes the dependency on having an accessible, working find command on your remote system.
Consider:
rmtfunc() {
set -- /home/remoteuser/logs/*.* # put contents of directory into $# array
for arg; do # ...for each item in that array...
[ -f "$arg" ] && exit 0 # ...if it's a file that exists, success
done
exit 1 # if nothing matched above, failure
}
# emit text that defines that function into the ssh command, then run same
if ssh remoteuser#host "$(declare -f rmtfunc); rmtfunc"; then
echo "Found remote logfiles"
else
echo "No remote logfiles exist"
fi
ANSWER:
Did find the following about the use of -e for a regular file.
http://www.cyberciti.biz/faq/unix-linux-test-existence-of-file-in-bash/
Even though it says "too many arguments" it does seem to test out OK.
ssh remoteuser#1.2.3.4 [ ! -e /home/remoteuser/logs/archive/*.zip ] && echo "File does not exists in the root" >> /home/localuser/files/dirlist.txt || echo "File does exists in the root" >> /home/localuser/files/dirlist.txt
Your script will work simply using double parenthesis:
ssh remoteuser#1.2.3.4 [[ ! -f /home/remoteuser/logs/archive/*.* ]] && echo "File does not exist in the root" >> /home/localuser/files/dirlist.txt
From man bash
Word splitting and pathname expansion are not performed on the words between the [[ and ]].
I have a bash script containing a function which is sourced by a number of different bash scripts. This function may fail based on its input, and I'd like to create logging within the function to identify what script(s) are causing failures.
E.g.,
source /path/to/function.sh
The closest I've come is this:
ps --no-heading -ocmd -p $$
This works well enough if the full file path is used to run the parent script, returning:
/bin/bash /path/to/parent.sh
But it fails to provide the full path if the parent script is run from a relative path, returning:
/bin/bash ./parent.sh
Ideally, I'd like a way to reliably return the parent script file path for both cases.
I suppose I could have each parent script pass its file path to the function (via $0 or similar), but that seems hard to enforce and not terribly elegant.
Any ideas, or alternative approaches? Should I not worry about the relative path case, and just use full/absolute file paths for everything?
Thanks!
I'm using Centos 5.9.
Bash version -
GNU bash, version 3.2.25(1)-release (x86_64-redhat-linux-gnu)
You can use readlink to follow all symbolic links to get an absolute path.
echo $(readlink -f $0)
As soon as the parent script starts export
"`pwd`/$0"
or so, into an env variable, say ORIG_SCRIPT, then in the function just use ORIG_SCRIPT.
You need to do this as soon as the script starts because $0 may be relative to the PWD and if you later change PWD before you need the value of ORIG_SCRIPT, it gets unnecessarily complicated.
Update:
Since you know the pid by $$, you may get something from /proc/<PID>/cmdline but I don't know how exactly this one works right now.
You could use ${BASH_SOURCE[1]} to get the script that calls the function but that is not always on absolute path form. You could get the absolute path of it by readlink -m, realpath, or other shell-script based solutions, but if your script changes directory from time to time, conversion of relative paths to absolute paths would no longer be accurate as those tools base from the current directory to get the actual form.
There's a workaround however but this requires that you won't change directories in your scripts before calling (sourcing) the script that contains the function. You would have to save the current directory in that script itself then base forming of absolute paths through that directory. You are free to change directories after the script has already been included. As an example:
ORIGINAL_PWD=$PWD
function x {
local CALLING_SCRIPT="${BASH_SOURCE[1]}"
if [[ -n $CALLING_SCRIPT ]]; then
if [[ $CALLING_SCRIPT == /* ]]; then
CALLING_SCRIPT=$(readlink -m "$CALLING_SCRIPT")
else
CALLING_SCRIPT=$(readlink -m "$ORIGINAL_PWD/$CALLING_SCRIPT")
fi
echo "Calling script: $CALLING_SCRIPT"
else
echo "Caller is not a script."
fi
}
Or
ORIGINAL_PWD=$PWD
function getabspath {
local -a T1 T2
local -i I=0
local IFS=/ A
case "$1" in
/*)
read -r -a T1 <<< "$1"
;;
*)
read -r -a T1 <<< "/$PWD/$1"
;;
esac
T2=()
for A in "${T1[#]}"; do
case "$A" in
..)
[[ I -ne 0 ]] && unset T2\[--I\]
continue
;;
.|'')
continue
;;
esac
T2[I++]=$A
done
case "$1" in
*/)
[[ I -ne 0 ]] && __="/${T2[*]}/" || __=/
;;
*)
[[ I -ne 0 ]] && __="/${T2[*]}" || __=/.
;;
esac
}
function x {
local CALLING_SCRIPT="${BASH_SOURCE[1]}"
if [[ -n $CALLING_SCRIPT ]]; then
if [[ $CALLING_SCRIPT == /* ]]; then
getabspath "$CALLING_SCRIPT"
else
getabspath "$ORIGINAL_PWD/$CALLING_SCRIPT"
fi
echo "Calling script: $__"
else
echo "Caller is not a script."
fi
}
You could also play around with FUNCNAME and BASH_LINENO to be more specific with the errors. I'm just not sure if they're already supported in Bash 3.2.
If you actually had Bash 4.0+ you could make use of associative arrays to map absolute paths with it but if there are two scripts with the same names or are called with almost similar names, one value could be overridden. There's no fix to that since we can't choose our keys from BASH_SOURCE.
Added Note: You could also prevent your script from being unnecessarily sourced multiple times as it only requires to be once through a solution like Shell Script Loader. You might find convenience through it as well.
This question already has answers here:
How do I get the directory where a Bash script is located from within the script itself?
(74 answers)
Closed 6 years ago.
I have a Bash script that needs to know its full path. I'm trying to find a broadly-compatible way of doing that without ending up with relative or funky-looking paths. I only need to support Bash, not sh, csh, etc.
What I've found so far:
The accepted answer to Getting the source directory of a Bash script from within addresses getting the path of the script via dirname $0, which is fine, but that may return a relative path (like .), which is a problem if you want to change directories in the script and have the path still point to the script's directory. Still, dirname will be part of the puzzle.
The accepted answer to Bash script absolute path with OS X (OS X specific, but the answer works regardless) gives a function that will test to see if $0 looks relative and if so will pre-pend $PWD to it. But the result can still have relative bits in it (although overall it's absolute) — for instance, if the script is t in the directory /usr/bin and you're in /usr and you type bin/../bin/t to run it (yes, that's convoluted), you end up with /usr/bin/../bin as the script's directory path. Which works, but...
The readlink solution on this page, which looks like this:
# Absolute path to this script. /home/user/bin/foo.sh
SCRIPT=$(readlink -f $0)
# Absolute path this script is in. /home/user/bin
SCRIPTPATH=`dirname $SCRIPT`
But readlink isn't POSIX and apparently the solution relies on GNU's readlink where BSD's won't work for some reason (I don't have access to a BSD-like system to check).
So, various ways of doing it, but they all have their caveats.
What would be a better way? Where "better" means:
Gives me the absolute path.
Takes out funky bits even when invoked in a convoluted way (see comment on #2 above). (E.g., at least moderately canonicalizes the path.)
Relies only on Bash-isms or things that are almost certain to be on most popular flavors of *nix systems (GNU/Linux, BSD and BSD-like systems like OS X, etc.).
Avoids calling external programs if possible (e.g., prefers Bash built-ins).
(Updated, thanks for the heads up, wich) It doesn't have to resolve symlinks (in fact, I'd kind of prefer it left them alone, but that's not a requirement).
Here's what I've come up with (edit: plus some tweaks provided by sfstewman, levigroker, Kyle Strand, and Rob Kennedy), that seems to mostly fit my "better" criteria:
SCRIPTPATH="$( cd -- "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
That SCRIPTPATH line seems particularly roundabout, but we need it rather than SCRIPTPATH=`pwd` in order to properly handle spaces and symlinks.
The inclusion of output redirection (>/dev/null 2>&1) handles the rare(?) case where cd might produce output that would interfere with the surrounding $( ... ) capture. (Such as cd being overridden to also ls a directory after switching to it.)
Note also that esoteric situations, such as executing a script that isn't coming from a file in an accessible file system at all (which is perfectly possible), is not catered to there (or in any of the other answers I've seen).
The -- after cd and before "$0" are in case the directory starts with a -.
I'm surprised that the realpath command hasn't been mentioned here. My understanding is that it is widely portable / ported.
Your initial solution becomes:
SCRIPT=$(realpath "$0")
SCRIPTPATH=$(dirname "$SCRIPT")
And to leave symbolic links unresolved per your preference:
SCRIPT=$(realpath -s "$0")
SCRIPTPATH=$(dirname "$SCRIPT")
The simplest way that I have found to get a full canonical path in Bash is to use cd and pwd:
ABSOLUTE_PATH="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/$(basename "${BASH_SOURCE[0]}")"
Using ${BASH_SOURCE[0]} instead of $0 produces the same behavior regardless of whether the script is invoked as <name> or source <name>.
I just had to revisit this issue today and found Get the source directory of a Bash script from within the script itself:
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
There's more variants at the linked answer, e.g. for the case where the script itself is a symlink.
Get the absolute path of a shell script
It does not use the -f option in readlink, and it should therefore work on BSD/Mac OS X.
Supports
source ./script (When called by the . dot operator)
Absolute path /path/to/script
Relative path like ./script
/path/dir1/../dir2/dir3/../script
When called from symlink
When symlink is nested eg) foo->dir1/dir2/bar bar->./../doe doe->script
When caller changes the scripts name
I am looking for corner cases where this code does not work. Please let me know.
Code
pushd . > /dev/null
SCRIPT_PATH="${BASH_SOURCE[0]}";
while([ -h "${SCRIPT_PATH}" ]); do
cd "`dirname "${SCRIPT_PATH}"`"
SCRIPT_PATH="$(readlink "`basename "${SCRIPT_PATH}"`")";
done
cd "`dirname "${SCRIPT_PATH}"`" > /dev/null
SCRIPT_PATH="`pwd`";
popd > /dev/null
echo "srcipt=[${SCRIPT_PATH}]"
echo "pwd =[`pwd`]"
Known issus
The script must be on disk somewhere. Let it be over a network. If you try to run this script from a PIPE it will not work
wget -o /dev/null -O - http://host.domain/dir/script.sh |bash
Technically speaking, it is undefined. Practically speaking, there is no sane way to detect this. (A co-process can not access the environment of the parent.)
Use:
SCRIPT_PATH=$(dirname `which $0`)
which prints to standard output the full path of the executable that would have been executed when the passed argument had been entered at the shell prompt (which is what $0 contains)
dirname strips the non-directory suffix from a file name.
Hence you end up with the full path of the script, no matter if the path was specified or not.
As realpath is not installed per default on my Linux system, the following works for me:
SCRIPT="$(readlink --canonicalize-existing "$0")"
SCRIPTPATH="$(dirname "$SCRIPT")"
$SCRIPT will contain the real file path to the script and $SCRIPTPATH the real path of the directory containing the script.
Before using this read the comments of this answer.
Easy to read? Below is an alternative. It ignores symlinks
#!/bin/bash
currentDir=$(
cd $(dirname "$0")
pwd
)
echo -n "current "
pwd
echo script $currentDir
Since I posted the above answer a couple years ago, I've evolved my practice to using this linux specific paradigm, which properly handles symlinks:
ORIGIN=$(dirname $(readlink -f $0))
Simply:
BASEDIR=$(readlink -f $0 | xargs dirname)
Fancy operators are not needed.
You may try to define the following variable:
CWD="$(cd -P -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
Or you can try the following function in Bash:
realpath () {
[[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}
This function takes one argument. If the argument already has an absolute path, print it as it is, otherwise print $PWD variable + filename argument (without ./ prefix).
Related:
Bash script absolute path with OS X
Get the source directory of a Bash script from within the script itself
Answering this question very late, but I use:
SCRIPT=$( readlink -m $( type -p ${0} )) # Full path to script handling Symlinks
BASE_DIR=`dirname "${SCRIPT}"` # Directory script is run in
NAME=`basename "${SCRIPT}"` # Actual name of script even if linked
We have placed our own product realpath-lib on GitHub for free and unencumbered community use.
Shameless plug but with this Bash library you can:
get_realpath <absolute|relative|symlink|local file>
This function is the core of the library:
function get_realpath() {
if [[ -f "$1" ]]
then
# file *must* exist
if cd "$(echo "${1%/*}")" &>/dev/null
then
# file *may* not be local
# exception is ./file.ext
# try 'cd .; cd -;' *works!*
local tmppwd="$PWD"
cd - &>/dev/null
else
# file *must* be local
local tmppwd="$PWD"
fi
else
# file *cannot* exist
return 1 # failure
fi
# reassemble realpath
echo "$tmppwd"/"${1##*/}"
return 0 # success
}
It doesn't require any external dependencies, just Bash 4+. Also contains functions to get_dirname, get_filename, get_stemname and validate_path validate_realpath. It's free, clean, simple and well documented, so it can be used for learning purposes too, and no doubt can be improved. Try it across platforms.
Update: After some review and testing we have replaced the above function with something that achieves the same result (without using dirname, only pure Bash) but with better efficiency:
function get_realpath() {
[[ ! -f "$1" ]] && return 1 # failure : file does not exist.
[[ -n "$no_symlinks" ]] && local pwdp='pwd -P' || local pwdp='pwd' # do symlinks.
echo "$( cd "$( echo "${1%/*}" )" 2>/dev/null; $pwdp )"/"${1##*/}" # echo result.
return 0 # success
}
This also includes an environment setting no_symlinks that provides the ability to resolve symlinks to the physical system. By default it keeps symlinks intact.
Considering this issue again: there is a very popular solution that is referenced within this thread that has its origin here:
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
I have stayed away from this solution because of the use of dirname - it can present cross-platform difficulties, particularly if a script needs to be locked down for security reasons. But as a pure Bash alternative, how about using:
DIR="$( cd "$( echo "${BASH_SOURCE[0]%/*}" )" && pwd )"
Would this be an option?
If we use Bash I believe this is the most convenient way as it doesn't require calls to any external commands:
THIS_PATH="${BASH_SOURCE[0]}";
THIS_DIR=$(dirname $THIS_PATH)
The accepted solution has the inconvenient (for me) to not be "source-able":
if you call it from a "source ../../yourScript", $0 would be "bash"!
The following function (for bash >= 3.0) gives me the right path, however the script might be called (directly or through source, with an absolute or a relative path):
(by "right path", I mean the full absolute path of the script being called, even when called from another path, directly or with "source")
#!/bin/bash
echo $0 executed
function bashscriptpath() {
local _sp=$1
local ascript="$0"
local asp="$(dirname $0)"
#echo "b1 asp '$asp', b1 ascript '$ascript'"
if [[ "$asp" == "." && "$ascript" != "bash" && "$ascript" != "./.bashrc" ]] ; then asp="${BASH_SOURCE[0]%/*}"
elif [[ "$asp" == "." && "$ascript" == "./.bashrc" ]] ; then asp=$(pwd)
else
if [[ "$ascript" == "bash" ]] ; then
ascript=${BASH_SOURCE[0]}
asp="$(dirname $ascript)"
fi
#echo "b2 asp '$asp', b2 ascript '$ascript'"
if [[ "${ascript#/}" != "$ascript" ]]; then asp=$asp ;
elif [[ "${ascript#../}" != "$ascript" ]]; then
asp=$(pwd)
while [[ "${ascript#../}" != "$ascript" ]]; do
asp=${asp%/*}
ascript=${ascript#../}
done
elif [[ "${ascript#*/}" != "$ascript" ]]; then
if [[ "$asp" == "." ]] ; then asp=$(pwd) ; else asp="$(pwd)/${asp}"; fi
fi
fi
eval $_sp="'$asp'"
}
bashscriptpath H
export H=${H}
The key is to detect the "source" case and to use ${BASH_SOURCE[0]} to get back the actual script.
One liner
`dirname $(realpath $0)`
Bourne shell (sh) compliant way:
SCRIPT_HOME=`dirname $0 | while read a; do cd $a && pwd && break; done`
Perhaps the accepted answer to the following question may be of help.
How can I get the behavior of GNU's readlink -f on a Mac?
Given that you just want to canonicalize the name you get from concatenating $PWD and $0 (assuming that $0 is not absolute to begin with), just use a series of regex replacements along the line of abs_dir=${abs_dir//\/.\//\/} and such.
Yes, I know it looks horrible, but it'll work and is pure Bash.
Try this:
cd $(dirname $([ -L $0 ] && readlink -f $0 || echo $0))
I have used the following approach successfully for a while (not on OS X though), and it only uses a shell built-in and handles the 'source foobar.sh' case as far as I have seen.
One issue with the (hastily put together) example code below is that the function uses $PWD which may or may not be correct at the time of the function call. So that needs to be handled.
#!/bin/bash
function canonical_path() {
# Handle relative vs absolute path
[ ${1:0:1} == '/' ] && x=$1 || x=$PWD/$1
# Change to dirname of x
cd ${x%/*}
# Combine new pwd with basename of x
echo $(pwd -P)/${x##*/}
cd $OLDPWD
}
echo $(canonical_path "${BASH_SOURCE[0]}")
type [
type cd
type echo
type pwd
Just for the hell of it I've done a bit of hacking on a script that does things purely textually, purely in Bash. I hope I caught all the edge cases.
Note that the ${var//pat/repl} that I mentioned in the other answer doesn't work since you can't make it replace only the shortest possible match, which is a problem for replacing /foo/../ as e.g. /*/../ will take everything before it, not just a single entry. And since these patterns aren't really regexes I don't see how that can be made to work. So here's the nicely convoluted solution I came up with, enjoy. ;)
By the way, let me know if you find any unhandled edge cases.
#!/bin/bash
canonicalize_path() {
local path="$1"
OIFS="$IFS"
IFS=$'/'
read -a parts < <(echo "$path")
IFS="$OIFS"
local i=${#parts[#]}
local j=0
local back=0
local -a rev_canon
while (($i > 0)); do
((i--))
case "${parts[$i]}" in
""|.) ;;
..) ((back++));;
*) if (($back > 0)); then
((back--))
else
rev_canon[j]="${parts[$i]}"
((j++))
fi;;
esac
done
while (($j > 0)); do
((j--))
echo -n "/${rev_canon[$j]}"
done
echo
}
canonicalize_path "/.././..////../foo/./bar//foo/bar/.././bar/../foo/bar/./../..//../foo///bar/"
Yet another way to do this:
shopt -s extglob
selfpath=$0
selfdir=${selfpath%%+([!/])}
while [[ -L "$selfpath" ]];do
selfpath=$(readlink "$selfpath")
if [[ ! "$selfpath" =~ ^/ ]];then
selfpath=${selfdir}${selfpath}
fi
selfdir=${selfpath%%+([!/])}
done
echo $selfpath $selfdir
More simply, this is what works for me:
MY_DIR=`dirname $0`
source $MY_DIR/_inc_db.sh
I have a problem to manage long paths. How can I get quickly to paths like
/Users/User/.../.../.../.../.../Dev/C/card.c
I tried an alias
alias cd C='cd /Users/User/.../.../.../.../.../Dev/C'
but I am unable to do aliases for two separate words. I have long lists of Bash aliases and paths in CDPATH, so I am hesitating to make them more. How can manage long paths?
[Ideas for Replies]
The user litb's reply revealed some of my problems in the management. Things, such as "CTRL+R", "!-3:1:2:4:x" and "incremental search", are hard for me. They probably help in navigating long directories and, in the sense, management.
Using symlinks is probably the best idea; but you can do it even easier than dumping them all into your home directory.
As you mentioned, BASH has a feature called CDPATH which comes in really handy here.
Just make a hidden folder in your homedir (so it doesn't clutter your homedir too much):
$ mkdir ~/.paths
$ cd ~/.paths
$ ln -s /my/very/long/path/name/to/my/project project
$ ln -s /some/other/very/long/path/to/my/backups backups
$ echo 'CDPATH=~/.paths' >> ~/.bashrc
$ source ~/.bashrc
This creates a directory in your homedir called ".paths" which contains symlinks to all your long directory locations which you regularly use, then sets the CDPATH bash variable to that directory (in your .bashrc) and re-reads the .bashrc file.
Now, you can go to any of those paths from anywhere:
$ cd project
$ cd backups
Leaving you with a short CDPATH, no cluttering aliasses, and more importantly: A really easy way to navigate to those long paths from other applications, such as UI applications, by just going into ~/.paths or adding that directory into your UI application's sidebar or so.
Probably the easiest all-round solution you can have.
Consider using symbolic links. I have a ~/work/ directory where I place symlinks to all my current projects.
You may also use shell variables:
c='/Users/User/.../.../.../.../.../Dev/C'
Then:
cd "$c"
Create symlinks in your home directory (or somewhere else of your choosing)
ln -s longDirectoryPath ~/MySymLinkName
See man ln for more details.
Probably the easiest solution is to use:
alias cdc='cd /Users/User/.../.../.../.../.../Dev/C'
alias cdbin='cd /Users/User/.../.../.../.../.../Dev/bin'
alias cdtst='cd /Users/User/.../.../.../.../.../Dev/tst'
if you're only really working on one project at a time. If you work on multiple projects, you could have another alias which changed the directories within those aliases above.
So, you'd use something like:
proj game17
cdc
make
proj roman_numerals
cdbin
rm -f *
proj game17 ; cdc
Since this is a useful thing to have, I decided to put together a series of scripts that can be used. They're all based aroung a configuration file that you place in your home directory, along with aliases to source scripts. The file "~/.cdx_data" is of the form:
scrabble:top=~/dev/scrabble
scrabble:src=~/dev/scrabble/src
scrabble:bin=~/dev/scrabble/bin
sudoku:top=~/dev/scrabble
sudoku:src=~/dev/scrabble/src
sudoku:bin=~/dev/scrabble/bin
sudoku:data=~/dev/scrabble/data
and lists all the relevant projects (scrabble and sodoku in this case) and their directories (which may be different for each project, but have top, bin, src and data in this example).
The first action is to initialize stuff, so put:
. ~/.cdx_init
at the end of your .bash_profile and create the "~/.cdx_init" file as:
alias cdxl='. ~/.cdx_list'
alias projl='. ~/.cdx_projlist'
alias cdx='. ~/.cdx_goto'
alias proj='. ~/.cdx_proj'
This sets up the four aliases to source the files which I'll include below. Usage is:
cdxl - List all directories in current project.
projl - List all projects.
proj - Show current project.
proj <p> - Set current project to <p> (if allowed).
cdx - Show current project/directory and expected/actual real
directory, since they can get out of sync if you mix cd and cdx.
cdx . - Set actual real directory to expected directory (in other words,
get them back into sync).
cdx <d> - Set directory to <d> (if allowed).
The actual script follow. First, ".cdx_list" which just lists the allowed directories in the current project (pipelines are broken into multiple lines for readability but they should all be on one line).
echo "Possible directories are:"
cat ~/.cdx_data
| grep "^${CDX_PROJ}:"
| sed -e 's/^.*://' -e 's/=.*$//'
| sort -u
| sed 's/^/ /'
Similarly, ".cdx_projlist" shows all the possible projects:
echo "Possible projects are:"
cat ~/.cdx_data
| grep ':'
| sed 's/:.*$//'
| sort -u
| sed 's/^/ /'
In the meaty scripts, ".cdx_proj" sets and/or shows the current project:
if [[ "$1" != "" ]] ; then
grep "^$1:" ~/.cdx_data >/dev/null 2>&1
if [[ $? != 0 ]] ; then
echo "No project name '$1'."
projl
else
export CDX_PROJ="$1"
fi
fi
echo "Current project is: [${CDX_PROJ}]"
and ".cdx_goto" is the same for directories within the project:
if [[ "$1" == "." ]] ; then
CDX_TMP="${CDX_DIR}"
else
CDX_TMP="$1"
fi
if [[ "${CDX_TMP}" != "" ]] ; then
grep "^${CDX_PROJ}:${CDX_TMP}=" ~/.cdx_data >/dev/null 2>&1
if [[ $? != 0 ]] ; then
echo "No directory name '${CDX_TMP}' for project '${CDX_PROJ}'."
cdxl
else
export CDX_DIR="${CDX_TMP}"
cd $(grep "^${CDX_PROJ}:${CDX_DIR}=" ~/.cdx_data
| sed 's/^.*=//'
| head -1
| sed "s:^~:$HOME:")
fi
fi
CDX_TMP=$(grep "^${CDX_PROJ}:${CDX_DIR}=" ~/.cdx_data
| sed 's/^.*=//'
| head -1
| sed "s:^~:$HOME:")
echo "Current project is: [${CDX_PROJ}]"
echo "Current directory is: [${CDX_DIR}]"
echo " [${CDX_TMP}]"
echo "Actual directory is: [${PWD}]"
unset CDX_TMP
It uses three environment variables which are reserved for its own use: "CDX_PROJ", "CDX_DIR" and "CDX_TMP". Other than those and the afore-mentioned files and aliases, there are no other resources used. It's the simplest, yet most adaptable solution I could come up with. Best of luck.
Revisiting. Today I received this link from a social bookmarking site, then I immediately remembered this question:
Navigation with bm
We keep a simple, plain text bookmarks
file and use a tool called bm to do
the look-ups. The tool can also be
used to edit the bookmark index
dynamically as shown below where we
add the directories from the previous
example to the index.
Once i cd'ed into such a long directory, i have that in the history. Then i just type Ctrl-R for the "(reverse-i-search)" prompt and type in a few characters, like Dev/C that appear somewhere in the path, and it shows me the command what i issued back then and i can easily jump to it again.
That works pretty well in practice. Because it won't find an entry if you haven't typed that path for quite some time, which would mean doing work to make things easier probably wouldn't be worth the time. But it definitely will find it if you used it recently. Which is exactly what i need.
In some way, it's a self-organizing cache for long commands & path-names :)
You might want to consider using a script like this in your .bashrc. I've used it on a daily basis ever since I read that post. Pretty bloody useful.
The user jhs suggested Pushd and Popd-commands. I share here some of my Bash-scripts that I found in Unix Power Tools -book. They are very cool when your directories get a way too long :)
#Moving fast between directories
alias pd=pushd
alias pd2='pushd +2'
alias pd3='pushd +3'
alias pd4='pushd +4'
The command 'pushd +n' "rotates" the stack. The reverse command 'popd +n' deletes the n entry of the stack. If your stack gets too long, use 'repeat n popd'. For examle, your stack is 12 directories long:
repeat 11 popd
When you want to see your stack, write 'pushd'. For further reading, I recommend the book on pages 625-626.
In your .bashrc find PS1='${debian_chroot:+($debian_chroot)}[\033[01;32m]\u#\h[\033[00m]:[\033[01;34m]
\W[\033[00m]\$ '
and replace the \w with \W.I already have it changed here. This will only give you the main directory where you are working. You can get the full directory by typing pwd
There are fundamental well-known ideas, like creating aliases:
alias cdfoo="cd /long/path/to/foo"
and also "dropping pebbles"
export foo=/long/path/to/foo
and also making the above "project-based". I use 'ticket based' directories.
topdir=ticket_12345
alias cdfoo="cd home/me/sandbox/$topdir/long/path/to/foo"
export foo="/home/me/sandbox/$topdir/long/path/to/foo"
but beyond all this, sometimes it's just handy to jump back and forth to where you've been recently, using command-line menus. (pushd and popd are cumbersome, IMHO).
I use acd_func.sh (listed below). Once defined, you can do
cd --
to see a list of recent directories, with a numerical menu
cd -2
to go to the second-most recent directory.
Very easy to use, very handy.
Here's the code:
# Insert into .profile, .bash_profile or wherever
# acd_func 1.0.5, 10-nov-2004
# petar marinov, http:/geocities.com/h2428, this is public domain
cd_func ()
{
local x2 the_new_dir adir index
local -i cnt
if [[ $1 == "--" ]]; then
dirs -v
return 0
fi
the_new_dir=$1
[[ -z $1 ]] && the_new_dir=$HOME
if [[ ${the_new_dir:0:1} == '-' ]]; then
#
# Extract dir N from dirs
index=${the_new_dir:1}
[[ -z $index ]] && index=1
adir=$(dirs +$index)
[[ -z $adir ]] && return 1
the_new_dir=$adir
fi
#
# '~' has to be substituted by ${HOME}
[[ ${the_new_dir:0:1} == '~' ]] && the_new_dir="${HOME}${the_new_dir:1}"
#
# Now change to the new dir and add to the top of the stack
pushd "${the_new_dir}" > /dev/null
[[ $? -ne 0 ]] && return 1
the_new_dir=$(pwd)
#
# Trim down everything beyond 11th entry
popd -n +11 2>/dev/null 1>/dev/null
#
# Remove any other occurence of this dir, skipping the top of the stack
for ((cnt=1; cnt <= 10; cnt++)); do
x2=$(dirs +${cnt} 2>/dev/null)
[[ $? -ne 0 ]] && return 0
[[ ${x2:0:1} == '~' ]] && x2="${HOME}${x2:1}"
if [[ "${x2}" == "${the_new_dir}" ]]; then
popd -n +$cnt 2>/dev/null 1>/dev/null
cnt=cnt-1
fi
done
return 0
}
alias cd=cd_func
if [[ $BASH_VERSION > "2.05a" ]]; then
# ctrl+w shows the menu
bind -x "\"\C-w\":cd_func -- ;"
fi
This might also be a useful function to put in your .bashrc; it moves up either a number of directories, or to a named directory, i.e. if you're in /a/b/c/d/ you can do up 3 or up a to end up in a.
I have no idea where I found this; if you know, please comment or add the attribution.
function up()
{
dir=""
if [ -z "$1" ]; then
dir=..
elif [[ $1 =~ ^[0-9]+$ ]]; then
x=0
while [ $x -lt ${1:-1} ]; do
dir=${dir}../
x=$(($x+1))
done
else
dir=${PWD%/$1/*}/$1
fi
cd "$dir";
}
If you want to switch to zsh, this is very easy-- just use "alias -g" (global alias, i.e. an alias that works anywhere in the command, not just the first word).
# alias -g c=/my/super/long/dir/name
# cd c
# pwd
/my/super/long/dir/name
In bash, I think the closest thing you'll get to 'aliasing' style is to write a function:
function ccd {
case "$1" in
c) cd /blah/blah/blah/long/path/number/one ;;
foo) cd /blah/blah/totally/different path ;;
"multiword phrase") cd /tmp ;;
esac
}
This means using something other than "cd" as the command when you want a shortcut, but other than that, it's flexible; you can also add an "ls" to the function so that it always reminds you what's in the directory after you cd, etc.
(Note that to use a multiword argument as above, you need to quote it on the command line, like this:
ccd "multiword phrase"
so it's not really all that convenient. But it'll work if you need to.)
Based on Andrew Medico's suggestion, check out J
Look into pushd, which allows you to maintain a stack of directories which you can push onto, pop off of, or rearrange.
Check out autojmp or dirmarks
Management requires both fast creation and removal of directories. Create many directiories:
mkdir -p user/new_dir/new/_dir/.../new_dir
Remove recursively many directories (be very careful when you are in lower directories!):
rm -r dir/.../new_dir/
For further reading, the cheat sheet may help you:
http://www.scribd.com/doc/2082838/Bash-Command-Line-History-Cheat-Sheet
It contains some nuggets, but I find it rather hard to read. I cannot get commands, like Meta+>, working. They probably help you in navigating long directories.
I realize the question is pretty old, but none of the scripts out there satisfied me, so I wrote a new one.
Here's the requirements I had in mind:
1) Use only bash commands -- I intend to use this on many different unices -- Linux, cygwin, HP-UX, AIX, and a couple others, so I couldn't depend on grep being consistent. Luckily I do have bash everywhere I work.
2) Short code -- I wanted to be able to bind this to a key in GNU screen, and just hit that key to paste the script into the current bash shell I'm using, so that I don't have to setup bash profiles on every system I use. Anything super long would be annoying and take too much time to paste.
3) No file usage -- Don't want to be littering shared logons with random files.
4) Act just like "cd" in the normal case. Don't want to have to think about which command to use before I start typing.
5) Provide "up" usage like this answer: How to manage Long Paths in Bash?
6) Keep a list of recently used directories, and switch to the most recent.
Here's the script:
#Jump History - Isaiah Damron
function jfind() {
lp=${JNHIST//==${PWD}==/==}
lp=${lp%%${lp#==*$1*==}}
lp=${lp##${lp%==*$1*==*}}
lp=${lp//==/}
[[ -d "$lp" ]] && echo $lp && return 0
return 1;
}
function jadd() {
[[ -z "$JNHIST" ]] && export JNHIST='=='
[[ 3000 -lt ${#JNHIST} ]] && export JNHIST=${JNHIST:0:3000} && export JNHIST="${JNHIST%==*}=="
export JNHIST="==$PWD${JNHIST//==${PWD}==/==}"
}
function j() {
{ cd $* 2> /dev/null && jadd; } \
|| { cd ${PWD/$1*/}$1 2> /dev/null && jadd; } \
|| { jfind $1 \
&& { cd $( jfind $1 ) 2> /dev/null && jadd; } ; } \
|| cd $*
}
function jh() {
[[ -z "$1" ]] && echo -e ${JNHIST//==/\\n}
[[ -n "$1" ]] && jfind $1 && cd $(jfind $1) && jadd
}
Usage:
jh [parameters]
If called on its own, without any parameters, it outputs the current history list. If it has a parameter, then it searches through the history for the most recently used directory that contains the string $1, and cd's to it.
j {parameters}
Does cd parameters. If that fails, it checks if any of the parent directories of $PWD match $1, and cd's to it. If that fails, then it calls jh $1. If that fails, then it outputs the result of cd parameters
Note: I used '==' as an internal separator. Hopefully you don't have any directories that contain a '==', but if you do you'll have to change around the script. Just :%s/==/whatever/g
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 also resolving ~username notation at the same time.
If the target is a directory, it might be possible to chdir() into the directory and then call getcwd(), but I really want to do this from a shell script rather than writing a C helper. Unfortunately, shells have a tendency to try to hide the existence of symlinks from the user (this is bash on OS X):
$ ls -ld foo bar
drwxr-xr-x 2 greg greg 68 Aug 11 22:36 bar
lrwxr-xr-x 1 greg greg 3 Aug 11 22:36 foo -> bar
$ cd foo
$ pwd
/Users/greg/tmp/foo
$
What I want is a function resolve() such that when executed from the tmp directory in the above example, resolve("foo") == "/Users/greg/tmp/bar".
readlink -f "$path"
Editor's note: The above works with GNU readlink and FreeBSD/PC-BSD/OpenBSD readlink, but not on OS X as of 10.11.
GNU readlink offers additional, related options, such as -m for resolving a symlink whether or not the ultimate target exists.
Note since GNU coreutils 8.15 (2012-01-06), there is a realpath program available that is less obtuse and more flexible than the above. It's also compatible with the FreeBSD util of the same name. It also includes functionality to generate a relative path between two files.
realpath $path
[Admin addition below from comment by halloleo —danorton]
For Mac OS X (through at least 10.11.x), use readlink without the -f option:
readlink $path
Editor's note: This will not resolve symlinks recursively and thus won't report the ultimate target; e.g., given symlink a that points to b, which in turn points to c, this will only report b (and won't ensure that it is output as an absolute path).
Use the following perl command on OS X to fill the gap of the missing readlink -f functionality:
perl -MCwd -le 'print Cwd::abs_path(shift)' "$path"
According to the standards, pwd -P should return the path with symlinks resolved.
C function char *getcwd(char *buf, size_t size) from unistd.h should have the same behaviour.
getcwd
pwd
"pwd -P" seems to work if you just want the directory, but if for some reason you want the name of the actual executable I don't think that helps. Here's my solution:
#!/bin/bash
# get the absolute path of the executable
SELF_PATH=$(cd -P -- "$(dirname -- "$0")" && pwd -P) && SELF_PATH=$SELF_PATH/$(basename -- "$0")
# resolve symlinks
while [[ -h $SELF_PATH ]]; do
# 1) cd to directory of the symlink
# 2) cd to the directory of where the symlink points
# 3) get the pwd
# 4) append the basename
DIR=$(dirname -- "$SELF_PATH")
SYM=$(readlink "$SELF_PATH")
SELF_PATH=$(cd "$DIR" && cd "$(dirname -- "$SYM")" && pwd)/$(basename -- "$SYM")
done
One of my favorites is realpath foo
realpath - return the canonicalized absolute pathname
realpath expands all symbolic links and resolves references to '/./', '/../' and extra '/' characters in the null terminated string named by path and
stores the canonicalized absolute pathname in the buffer of size PATH_MAX named by resolved_path. The resulting path will have no symbolic link, '/./' or
'/../' components.
readlink -e [filepath]
seems to be exactly what you're asking for
- it accepts an arbirary path, resolves all symlinks, and returns the "real" path
- and it's "standard *nix" that likely all systems already have
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|"; }
Putting some of the given solutions together, knowing that readlink is available on most systems, but needs different arguments, this works well for me on OSX and Debian. I'm not sure about BSD systems. Maybe the condition needs to be [[ $OSTYPE != darwin* ]] to exclude -f from OSX only.
#!/bin/bash
MY_DIR=$( cd $(dirname $(readlink `[[ $OSTYPE == linux* ]] && echo "-f"` $0)) ; pwd -P)
echo "$MY_DIR"
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'))")
Common shell scripts often have to find their "home" directory even if they are invoked as a symlink. The script thus have to find their "real" position from just $0.
cat `mvn`
on my system prints a script containing the following, which should be a good hint at what you need.
if [ -z "$M2_HOME" ] ; then
## resolve links - $0 may be a link to maven's home
PRG="$0"
# need this for relative symlinks
while [ -h "$PRG" ] ; do
ls=`ls -ld "$PRG"`
link=`expr "$ls" : '.*-> \(.*\)$'`
if expr "$link" : '/.*' > /dev/null; then
PRG="$link"
else
PRG="`dirname "$PRG"`/$link"
fi
done
saveddir=`pwd`
M2_HOME=`dirname "$PRG"`/..
# make it fully qualified
M2_HOME=`cd "$M2_HOME" && pwd`
Note: I believe this to be a solid, portable, ready-made solution, which is invariably lengthy for that very reason.
Below is a fully POSIX-compliant script / function that is therefore cross-platform (works on macOS too, whose readlink still doesn't support -f as of 10.12 (Sierra)) - it uses only POSIX shell language features and only POSIX-compliant utility calls.
It is a portable implementation of GNU's readlink -e (the stricter version of readlink -f).
You can run the script with sh or source the function in bash, ksh, and zsh:
For instance, inside a script you can use it as follows to get the running's script true directory of origin, with symlinks resolved:
trueScriptDir=$(dirname -- "$(rreadlink "$0")")
rreadlink script / function definition:
The code was adapted with gratitude from this answer.
I've also created a bash-based stand-alone utility version here, which you can install with
npm install rreadlink -g, if you have Node.js installed.
#!/bin/sh
# SYNOPSIS
# rreadlink <fileOrDirPath>
# DESCRIPTION
# Resolves <fileOrDirPath> to its ultimate target, if it is a symlink, and
# prints its canonical path. If it is not a symlink, its own canonical path
# is printed.
# A broken symlink causes an error that reports the non-existent target.
# LIMITATIONS
# - Won't work with filenames with embedded newlines or filenames containing
# the string ' -> '.
# COMPATIBILITY
# This is a fully POSIX-compliant implementation of what GNU readlink's
# -e option does.
# EXAMPLE
# In a shell script, use the following to get that script's true directory of origin:
# trueScriptDir=$(dirname -- "$(rreadlink "$0")")
rreadlink() ( # Execute the function in a *subshell* to localize variables and the effect of `cd`.
target=$1 fname= targetDir= CDPATH=
# Try to make the execution environment as predictable as possible:
# All commands below are invoked via `command`, so we must make sure that
# `command` itself is not redefined as an alias or shell function.
# (Note that command is too inconsistent across shells, so we don't use it.)
# `command` is a *builtin* in bash, dash, ksh, zsh, and some platforms do not
# even have an external utility version of it (e.g, Ubuntu).
# `command` bypasses aliases and shell functions and also finds builtins
# in bash, dash, and ksh. In zsh, option POSIX_BUILTINS must be turned on for
# that to happen.
{ \unalias command; \unset -f command; } >/dev/null 2>&1
[ -n "$ZSH_VERSION" ] && options[POSIX_BUILTINS]=on # make zsh find *builtins* with `command` too.
while :; do # Resolve potential symlinks until the ultimate target is found.
[ -L "$target" ] || [ -e "$target" ] || { command printf '%s\n' "ERROR: '$target' does not exist." >&2; return 1; }
command cd "$(command dirname -- "$target")" # Change to target dir; necessary for correct resolution of target path.
fname=$(command basename -- "$target") # Extract filename.
[ "$fname" = '/' ] && fname='' # !! curiously, `basename /` returns '/'
if [ -L "$fname" ]; then
# Extract [next] target path, which may be defined
# *relative* to the symlink's own directory.
# Note: We parse `ls -l` output to find the symlink target
# which is the only POSIX-compliant, albeit somewhat fragile, way.
target=$(command ls -l "$fname")
target=${target#* -> }
continue # Resolve [next] symlink target.
fi
break # Ultimate target reached.
done
targetDir=$(command pwd -P) # Get canonical dir. path
# Output the ultimate target's canonical path.
# Note that we manually resolve paths ending in /. and /.. to make sure we have a normalized path.
if [ "$fname" = '.' ]; then
command printf '%s\n' "${targetDir%/}"
elif [ "$fname" = '..' ]; then
# Caveat: something like /var/.. will resolve to /private (assuming /var# -> /private/var), i.e. the '..' is applied
# AFTER canonicalization.
command printf '%s\n' "$(command dirname -- "${targetDir}")"
else
command printf '%s\n' "${targetDir%/}/$fname"
fi
)
rreadlink "$#"
A tangent on security:
jarno, in reference to the function ensuring that builtin command is not shadowed by an alias or shell function of the same name, asks in a comment:
What if unalias or unset and [ are set as aliases or shell functions?
The motivation behind rreadlink ensuring that command has its original meaning is to use it to bypass (benign) convenience aliases and functions often used to shadow standard commands in interactive shells, such as redefining ls to include favorite options.
I think it's safe to say that unless you're dealing with an untrusted, malicious environment, worrying about unalias or unset - or, for that matter, while, do, ... - being redefined is not a concern.
There is something that the function must rely on to have its original meaning and behavior - there is no way around that.
That POSIX-like shells allow redefinition of builtins and even language keywords is inherently a security risk (and writing paranoid code is hard in general).
To address your concerns specifically:
The function relies on unalias and unset having their original meaning. Having them redefined as shell functions in a manner that alters their behavior would be a problem; redefinition as an alias is
not necessarily a concern, because quoting (part of) the command name (e.g., \unalias) bypasses aliases.
However, quoting is not an option for shell keywords (while, for, if, do, ...) and while shell keywords do take precedence over shell functions, in bash and zsh aliases have the highest precedence, so to guard against shell-keyword redefinitions you must run unalias with their names (although in non-interactive bash shells (such as scripts) aliases are not expanded by default - only if shopt -s expand_aliases is explicitly called first).
To ensure that unalias - as a builtin - has its original meaning, you must use \unset on it first, which requires that unset have its original meaning:
unset is a shell builtin, so to ensure that it is invoked as such, you'd have to make sure that it itself is not redefined as a function. While you can bypass an alias form with quoting, you cannot bypass a shell-function form - catch 22.
Thus, unless you can rely on unset to have its original meaning, from what I can tell, there is no guaranteed way to defend against all malicious redefinitions.
Is your path a directory, or might it be a file? If it's a directory, it's simple:
(cd "$DIR"; pwd -P)
However, if it might be a file, then this won't work:
DIR=$(cd $(dirname "$FILE"); pwd -P); echo "${DIR}/$(readlink "$FILE")"
because the symlink might resolve into a relative or full path.
On scripts I need to find the real path, so that I might reference configuration or other scripts installed together with it, I use this:
SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"
SOURCE="$(readlink "$SOURCE")"
[[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
done
You could set SOURCE to any file path. Basically, for as long as the path is a symlink, it resolves that symlink. The trick is in the last line of the loop. If the resolved symlink is absolute, it will use that as SOURCE. However, if it is relative, it will prepend the DIR for it, which was resolved into a real location by the simple trick I first described.
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"))/..
In case where pwd can't be used (e.g. calling a scripts from a different location), use realpath (with or without dirname):
$(dirname $(realpath $PATH_TO_BE_RESOLVED))
Works both when calling through (multiple) symlink(s) or when directly calling the script - from any location.
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.
Try this:
cd $(dirname $([ -L $0 ] && readlink -f $0 || echo $0))
Since I've run into this many times over the years, and this time around I needed a pure bash portable version that I could use on OSX and linux, I went ahead and wrote one:
The living version lives here:
https://github.com/keen99/shell-functions/tree/master/resolve_path
but for the sake of SO, here's the current version (I feel it's well tested..but I'm open to feedback!)
Might not be difficult to make it work for plain bourne shell (sh), but I didn't try...I like $FUNCNAME too much. :)
#!/bin/bash
resolve_path() {
#I'm bash only, please!
# usage: resolve_path <a file or directory>
# follows symlinks and relative paths, returns a full real path
#
local owd="$PWD"
#echo "$FUNCNAME for $1" >&2
local opath="$1"
local npath=""
local obase=$(basename "$opath")
local odir=$(dirname "$opath")
if [[ -L "$opath" ]]
then
#it's a link.
#file or directory, we want to cd into it's dir
cd $odir
#then extract where the link points.
npath=$(readlink "$obase")
#have to -L BEFORE we -f, because -f includes -L :(
if [[ -L $npath ]]
then
#the link points to another symlink, so go follow that.
resolve_path "$npath"
#and finish out early, we're done.
return $?
#done
elif [[ -f $npath ]]
#the link points to a file.
then
#get the dir for the new file
nbase=$(basename $npath)
npath=$(dirname $npath)
cd "$npath"
ndir=$(pwd -P)
retval=0
#done
elif [[ -d $npath ]]
then
#the link points to a directory.
cd "$npath"
ndir=$(pwd -P)
retval=0
#done
else
echo "$FUNCNAME: ERROR: unknown condition inside link!!" >&2
echo "opath [[ $opath ]]" >&2
echo "npath [[ $npath ]]" >&2
return 1
fi
else
if ! [[ -e "$opath" ]]
then
echo "$FUNCNAME: $opath: No such file or directory" >&2
return 1
#and break early
elif [[ -d "$opath" ]]
then
cd "$opath"
ndir=$(pwd -P)
retval=0
#done
elif [[ -f "$opath" ]]
then
cd $odir
ndir=$(pwd -P)
nbase=$(basename "$opath")
retval=0
#done
else
echo "$FUNCNAME: ERROR: unknown condition outside link!!" >&2
echo "opath [[ $opath ]]" >&2
return 1
fi
fi
#now assemble our output
echo -n "$ndir"
if [[ "x${nbase:=}" != "x" ]]
then
echo "/$nbase"
else
echo
fi
#now return to where we were
cd "$owd"
return $retval
}
here's a classic example, thanks to brew:
%% ls -l `which mvn`
lrwxr-xr-x 1 draistrick 502 29 Dec 17 10:50 /usr/local/bin/mvn# -> ../Cellar/maven/3.2.3/bin/mvn
use this function and it will return the -real- path:
%% cat test.sh
#!/bin/bash
. resolve_path.inc
echo
echo "relative symlinked path:"
which mvn
echo
echo "and the real path:"
resolve_path `which mvn`
%% test.sh
relative symlinked path:
/usr/local/bin/mvn
and the real path:
/usr/local/Cellar/maven/3.2.3/libexec/bin/mvn
To work around the Mac incompatibility, I came up with
echo `php -r "echo realpath('foo');"`
Not great but cross OS
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
}
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
My 2 cents. This function is POSIX compliant, and both the source and the destination can contain ->. However, I have not gotten it work with filenames that container newline or tabs, as ls in general has issues with those.
resolve_symlink() {
test -L "$1" && ls -l "$1" | awk -v SYMLINK="$1" '{ SL=(SYMLINK)" -> "; i=index($0, SL); s=substr($0, i+length(SL)); print s }'
}
I believe the solution here is the file command, with a custom magic file that only outputs the destination of the provided symlink.
This is the best solution, tested in Bash 3.2.57:
# Read a path (similar to `readlink`) recursively, until the physical path without any links (like `cd -P`) is found.
# Accepts any existing path, prints its physical path and exits `0`, exits `1` if some contained links don't exist.
# Motivation: `${BASH_SOURCE[0]}` often contains links; using it directly to extract your project's path may fail.
#
# Example: Safely `source` a file located relative to the current script
#
# source "$(dirname "$(rreadlink "${BASH_SOURCE[0]}")")/relative/script.sh"
#Inspiration: https://stackoverflow.com/a/51089005/6307827
rreadlink () {
declare p="$1" d l
while :; do
d="$(cd -P "$(dirname "$p")" && pwd)" || return $? #absolute path without symlinks
p="$d/$(basename "$p")"
if [ -h "$p" ]; then
l="$(readlink "$p")" || break
#A link must be resolved from its fully resolved parent dir.
d="$(cd "$d" && cd -P "$(dirname "$l")" && pwd)" || return $?
p="$d/$(basename "$l")"
else
break
fi
done
printf '%s\n' "$p"
}