[SOLVED] Shell rename with first 4 characters

Steve W · 04-19-2010, 05:25 AM

Well, I'm trying to do this as an "instant access" script from Nautilus. The idea is that if I had a few of these files that I wanted to chop off to their first four characters (and retain the extension), I would just select them, right click and select Scripts->File_chop.sh (or whatever), and it would do it, rather than using the command line. I thought it may be possible for the script to get its filenames from the files I had selected in Nautilus.

Looking at the ps2pdf script, that's exactly what it does. Somehow, it passes the name of the .ps file I have selected (only one file, I think) into the script. Is "for arg in $@" the same as "for each arg in $@"? Normally when you set up a for loop, it's doing something more than once. And what exactly is the purpose of $@? (I'd do a Google search for it, but it has trouble recognising the string '$@').

Steve

MTK358 · 04-19-2010, 07:07 AM

I don't use Nautilus or know much about it, but maybe Nautilus passes the selected files as arguments to the script?

I would try replacing the "[^.]*.*" (which matches all non-hidden (not starting with a dot) files) part of my script with "$@".

Steve W · 04-19-2010, 07:16 AM

Quote:

I would try replacing the "[^.]*.*" (which matches all non-hidden (not starting with a dot) files) part of my script with "$@".

Well the first thing I was looking at was the first line: I need something that says For Each File In Selection, or something. Once the script is locked into the loop, it needs to keep the extension and reduce the first bit to four characters. So I *think* the regular expression bit of the script works as it is. Could be wrong though...

Do you think I might be better off posting this in a Nautilus forum then? I mean, I'm not too sure where Nautilus finishes and scripting begins in this case!

Steve

MTK358 · 04-19-2010, 07:18 AM

I am still pretty sure that Nautilus would pass the files as arguments to the script, in which case this will work:

Code:

#!/bin/bash

for file in $@; do
	newname=$(echo "$file" | sed --regexp-extended 's:(.{1,4}).*(\.[^.]*):\1\2:')
	if [ "$file" != "$newname" ]; then
		if [ -e "$newname" ]; then # if $filename exists
			echo 'error: file "'"$newname"'" already exists!'
		else
			mv "$file" "$newname"
		fi
	fi
done

MTK358 · 04-19-2010, 07:22 AM

An explanation of the regex:

Code:

s:        Search/Replace

(.{1,4})  Match 1-4 of any character

.*        Match any amount of any character

(\.[^.]*) Match a dot followed by any amount of characters that aren't dots

:\1\2:    Print the match in the first ()-delimited group, followed by what matched the second ()-delimited group.

Steve W · 04-19-2010, 07:42 AM

Quote:

I am still pretty sure that Nautilus would pass the files as arguments to the script, in which case this will work:

No, it only works on the first file in the select. It does not iterate through all those files selected.

However, I did find on a Nautilus script site a piece of code to "concatenate selected files in one file and move the old ones to Trash". I can't figure out which bit might apply to my situation. Can you?

#!/bin/bash
# Marius Andreiana
# Licence: GPL
#

concat_file_name=$( echo $1 | sed s/'..$'/""/g )
#cd $NAUTILUS_SCRIPT_SELECTED_FILE_PATHS
for arg
do
echo "$arg" >> nautilus_script_files
done

cat $( cat nautilus_script_files | sort ) > $concat_file_name
rm -f nautilus_script_files

for arg
do
mv "$arg" ~/.Trash
done

MTK358 · 04-19-2010, 07:45 AM

It appears that Nautilus introduces a few of its own variables.

Sadly I can't help you from here because I don't use Nautilus and don't intend to.

Steve W · 04-19-2010, 07:59 AM

Ah, I see what's happening! The sample files I was using had spaces in them (which the files I will probably be doing this sort of thing on, will not). It can't handle filenames with spaces in. So your first script did work after all. Problem solved!

Thank you very much for your patience and assistance in this matter.

Steve

MTK358 · 04-19-2010, 08:02 AM

If your problem is solved, mark it as solved (in Thread Tools).