Bash script: symbolic linking all files with same extension in a directory

Katachi · 12-25-2006, 08:56 AM

First, this is my first bash script. Second off, it works. Third, its pretty pointless. Those caveats outta the way, my desire was to have a way to rename every file in a directory that was a certain extension, into files like <user selected string>1.extention. The directory where this takes place usually contains ~25 different files in the format of [UniqueUnintuitiveLabel]_Complicated_and_Long_Name_01_[38281809].foo or such. I just wanted something to instantly change all those ~25 filenames into something with a simpler name I could perform commands on, like a1.foo, a2.foo, a3.foo etc.

Anyways, this is the solution I came up with...

Code:

#!/bin/bash
echo "Enter the number of files:"
read foocount
echo "Enter an easy to type base name, such as an anacronym:"
read simple
echo "Enter the file extension(with period):"
read exten

#create a temporary file to contain all filenames
#of the user defined extention in the current directory
ls *"$exten" >> tempfile

#for each unmodified file name, create a symbolic link
#of the form <userdefinedname>1.
n=1
while [ $n -le $foocount ]
do
    filenamen=$(sed -n "$n{p;q;}" "tempfile")
    ln -s $filenamen $simple$n
    n=$((n+1))
done
rm tempfile

Is there a simpler/more elegant way to accomplish this? In particular, I have a feeling theres a way to get around the need for a stdout filled tempfile.

Symbolic links were used instead of "mv" because I need the original files to keep their names.

I know that TAB completion makes this script pretty useless, I really just wanted to learn some bash scripting.

Thanks.

jschiwal · 12-25-2006, 09:42 AM

Since the extension doesn't change, you could use file globing instead of manually counting the number of files that contain the extension:

Code:

#! /bin/bash
basename=$1; ext=$2
count=1
if [ "${#*}" != 2 ]; then cat << EOF
Usage: $0 basename extension
EOF
fi

for file in *.$ext; do
  ln -s "${file}" "$basename-$count"
  count=$(( ${count}+1 ))
done

I hope I didn't misunderstand your outcome.
This version takes the simple basename of the link and the extension from the parameters of the command.
The << EOF
...
EOF
part is a common technique. Instead of producing a bunch of echo statements, simply type in the message. Notice that $0 is expanded in the script. You can use this same technique to send emails to a group of other users, expanding some items read in to personalize the email.

I didn't comment my example as well as you did yours.