[SOLVED] bash script - return full path and filename

arifsaha · 03-31-2011, 11:16 AM

How about this one to get absolute path? Simpler, even local variables are not needed. Little modification will get you the file base name if needed, as soon as you can define its behaviour when you give directory as argument (should it be the last directory or empty string?).

Code:

function abspath {
	if [[ -d "$1" ]]
	then
		pushd "$1" >/dev/null
		pwd
		popd >/dev/null
	elif [[ -e $1 ]]
	then
		pushd $(dirname $1) >/dev/null
		echo $(pwd)/$(basename $1)
		popd >/dev/null
	else
		echo $1 does not exist! >&2
		return 127
	fi
}

konsolebox · 04-09-2011, 04:19 AM

you can try mine as well:

Code:

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
}

Code:

getabspath "/path/.././././to/somewhere/"
echo "$__"

getabspath ".././././....//path/.././././to/somewhere/with/somefile.ext"
echo "$__"

note that the path or files does not need to exist.

the function can also be modified to accept another argument which could represent the name of the variable which will hold the result. i.e. like

Code:

getabspath <path> <variable_name>

Andy Alt · 07-07-2011, 05:20 PM

Calling a binary from a bash script can sometimes be preferred. Here's some C code which can be compiled using gcc -Wall -o getpath getpath.c

Code:

//      getpath.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char **argv)
{	
	if (argc != 2)
		{
			printf("Getpath takes one filename or directory as a parameter\n");
			exit (1);
		}
	
	char AbsPath[strlen(argv[1] + 1)];
	realpath(argv[1],AbsPath);
	printf("%s\n",AbsPath);
	return 0;
}

So if desired, copy the code above to a plain text file called getpath.c and compile it. Then use "./getpath <filename>" If you put getpath is in your path somewhere, the ./ can be omitted.

fatso83 · 06-19-2012, 03:27 AM

The script from arifsaha was without doubt leaps and bounds better than any of the others; clean, simple and cross-platform compatible. Works just as well on BSD as on GNU based toolsets. I will try to give credit whenever I use it - which I suspect will be plenty more than the three applications so far :-)

Quote:

Originally Posted by arifsaha

How about this one to get absolute path? Simpler, even local variables are not needed.

Code:

function abspath {
	if [[ -d "$1" ]]
	then
		pushd "$1" >/dev/null
		pwd
		popd >/dev/null
	elif [[ -e $1 ]]
	then
		pushd $(dirname $1) >/dev/null
		echo $(pwd)/$(basename $1)
		popd >/dev/null
	else
		echo $1 does not exist! >&2
		return 127
	fi
}

pan64 · 06-19-2012, 03:34 AM

just one comment: instead basename and dirname you can use parameter substitution:

Code:

${var##*/}  # <== basename
${var%/*}   # <== dirname

_____________________________________
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Happy with solution ... mark as SOLVED
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fatso83 · 06-19-2012, 10:01 AM

I mentioned clean and simple; for the uninitiated, that looks like voodo

I prefer verbosity over terseness if the terseness comes with a reduction in readability.

pan64 · 06-19-2012, 11:11 AM

actually it is not really so simple: using parameter substitution will be processed inside the shell, using basename and dirname will fork another task, will open pipe therefore it costs more, much more. If you were familiar with bash enough you should not speak about readability problems in such cases....

fatso83 · 06-19-2012, 11:41 AM

Quote:

Originally Posted by pan64

If you were familiar with bash enough you should not speak about readability problems in such cases...

I have never claimed to be a bash expert, and for the case of the original script, one did not need to be either, which is why I liked it

For most people hacking together small scripts to get some job done it does not pay to invest time into learning the ins and outs of the various shell, which is why shell scripts should be mostly self-explanatory. Or just heavily commented

But the info on why parameter substitution might prove a better fit was very interesting (for me, at least), and put the matter into another perspective. Thanks for the info - nice to know!

konsolebox · 06-26-2012, 07:05 PM

Quote:

Originally Posted by fatso83

The script from arifsaha was without doubt leaps and bounds better than any of the others; clean, simple and cross-platform compatible. Works just as well on BSD as on GNU based toolsets. I will try to give credit whenever I use it - which I suspect will be plenty more than the three applications so far :-)

Unfortunately the directories need to exist in order for that to work. Also, you'll have to use external commands which is rather slower and require dependencies.

konsolebox · 06-26-2012, 07:09 PM

Check out my full post about getting absolute pathnames in all general shells and also for a binary format.

http://www.linuxquestions.org/questi...-scripts-3956/

Andy Alt · 07-06-2012, 12:10 AM

The realpath command was added to coreutils, as of version 8.15, I believe. Not the best solution yet -- not all *nix distros have it installed yet, and I couldn't say anything about Macs.

See also: GNU core utilities

fatso83 · 07-06-2012, 10:24 AM

Quote:

Originally Posted by Andy Alkaline

The realpath command was added to coreutils, as of version 8.15, I believe. Not the best solution yet -- not all *nix distros have it installed yet, and I couldn't say anything about Macs.

See also: GNU core utilities

Seems good - albeit it does not exist on Mac or on any of our servers (typically 3-5 years behind). So a cross-platform script comes in handy

fatso83 · 01-10-2013, 06:21 AM

I just tried the suggestions from pan64, but I was unable to make it work. Can anyone change the script above and make it work with parameter substitution? I have also searched the man page for bash on the "var##" pattern, and I cannot find anything referencing it.

Quote:

Originally Posted by pan64

just one comment: instead basename and dirname you can use parameter substitution:

Code:

${var##*/}  # <== basename
${var%/*}   # <== dirname

_____________________________________
If someone helps you, or you approve of what's posted, click the "Add to Reputation" button, on the left of the post.
Happy with solution ... mark as SOLVED
(located in the "thread tools")

pan64 · 01-10-2013, 06:39 AM

please open a new thread and specify your problem, or at least show us what you tried:

Code:

$ var=/a/v/b/n/f/e
$ echo ${var##*/}
e
$ echo ${var%/*}
/a/v/b/n/f
$

konsolebox · 01-10-2013, 09:11 AM

I wonder how my script could not provide the one you require that you have to go all the troubles.