Bash scripting -- parsing a directory path

int80 · 08-11-2009, 08:02 AM

Hi guys, I need to get the base path from a full path to a file.

/base/file/file.tar

I want to get "/base" from that. I know how to get the file and /base/file using basename and dirname and also that using sed, but I can't get the base dir.

Any help would be great.

PMP · 08-11-2009, 08:09 AM

Code:

echo /base/file/file.tar | cut -d "/" -f2

awk:

Code:

 echo /base/file/file.tar | awk -F"/" '{print "/"$2}'

pixellany · 08-11-2009, 08:27 AM

You are using "base" in 2 different ways, which is confusing.

Let's see if I understand correctly......Suppose you have "dir=/home/user/documents/myfile"

basename $dir gives: myfile

dirname $dir gives: /home/user/documents

You know how to do either one of these with SED, but you want to know how to get just "/home"

Try this:

Code:

echo $dir|sed 's%\(/[^/]*\).*%\1%'

If I got the question correct and/or you want the above decoded, please ask!!

pixellany · 08-11-2009, 08:31 AM

OK, so maybe SED is not the best for everything.......

In the "cut" and "awk" examples, why field #2?

PTrenholme · 08-11-2009, 08:40 AM

Quote:

Originally Posted by pixellany

OK, so maybe SED is not the best for everything.......

In the "cut" and "awk" examples, why field #2?

Because it (the directory name) precedes the second /, so it's the second field. (The empty string is a valid field value.)

pixellany · 08-11-2009, 08:46 AM

Quote:

Originally Posted by PTrenholme

Because it (the directory name) precedes the second /, so it's the second field. (The empty string is a valid field value.)

Obvious when you think about it---you don't need a field separator until you have a field......

Confusion opportunity:

Code:

 big dog bark   ## dog is the 3rd field
big dog bark    ## dog is the 2nd field

Maybe SED was better.......

PMP · 08-11-2009, 09:26 AM

vonbiber · 08-11-2009, 09:43 AM

Quote:

Originally Posted by int80

Hi guys, I need to get the base path from a full path to a file.

/base/file/file.tar

I want to get "/base" from that. I know how to get the file and /base/file using basename and dirname and also that using sed, but I can't get the base dir.

Any help would be great.

foo=/base/file/file.tar

echo ${foo%/*} | sed 's?^$/[^/]*$/.*$?\1?'

Actually if all you need is the first top directory, then
echo $foo | sed 's?^$/[^/]*$/.*$?\1?'
would do it
(${foo%/*} would give /base/file)

catkin · 08-11-2009, 10:06 AM

Code:

fullpath='/base/file/file.tar'
IFS='/' array=($fullpath)
echo "/${array[1]}"

That runs faster than using awk, cut or sed because no sub-process is required.

ghostdog74 · 08-11-2009, 10:38 AM

Quote:

Originally Posted by pixellany

Maybe SED was better.......

nah , don't think so.

PTrenholme · 08-11-2009, 12:32 PM

For what it's worth, here's a script that does it entirely in bash. With the "added value" that, by un-commenting the the commented lines, you get an array of the entire path. (If you're wondering, I wasn't familiar with the dirname and basname functions, so I was playing around.)

Code:

#!/bin/bash
topdir="$1"
name="$(dirname "$topdir")"
#i=0
while [ "$topdir" != "/" ];do
#  i=$(($i+1))
#  parse[$i]="$(basename "$topdir")"
  name="$topdir"
  topdir="$(dirname "$topdir")"
  [ "$topdir" = "." ] && topdir="$(pwd -P)"
done
echo "$name"
#while [ $i -gt 0 ]; do
#  echo -n " / ${parse[$i]}"
#  i=$(($i-1))
#done
#echo

C. Pappy · 05-27-2017, 09:53 AM

I recognize that this is a very old thread, but I think that the following solution could be generally useful because it demonstrates the power of bash pattern matching.

Code:

> cat t
[[ "$1" =~ ((/|)[^/]*)(/|) ]]
echo ${BASH_REMATCH[1]}
> t /base/file/file.tar
/base
> t base/file/file.tar
base
> t /base
/base
> t base
base
> t

>

BW-userx · 05-27-2017, 11:15 AM

Well if you know what you're working with in directory depth

Code:

userx%voider ⚡ testing ⚡> firstDir="/base/file/file.tar"
userx%voider ⚡ testing ⚡> BaseDir=${firstDir%/*/*}
userx%voider ⚡ testing ⚡> echo $BaseDir
/base

NevemTeve · 05-27-2017, 11:17 PM

Note: from '/base/file/file.tar' part 'file' might very well be a symlink to '/somewhere/else'

astrogeek · 05-27-2017, 11:33 PM

Welcome to LQ!

Quote:

Originally Posted by C. Pappy

I recognize that this is a very old thread...

Let's let old threads sleep peacefully, please.

If you have a specific question or your own use case similar to one in an inactive thread, please start your own thread and include the details of your own case. This prevents confusion that can arise from similar but not exactly the same constraints, and the resulting discussion necessary to discover and redefine those constraints.