changing filenames in a directory to a number within a loop

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# 1  
Old 12-07-2007
changing filenames in a directory to a number within a loop

hey guys. i'm new to shell scripting but not new to programming. i want to write a script that will take all the files in the current directory that end with a particular filetype and change all their names to a number in order. so, it would take all the jpg files and sort them in alphabetical order, then it would change their names from 1 all the way up to the end, so maybe 36 or something. whatever, until there's no more image files. this sounds like it would be a simple and short script to write, but i have no idea where to start. can anyone help me, or direct me to a similar script so i can hack it? thanks
# 2  
Old 12-07-2007
Here is a simple model to try -
let i=1
cd /path/to/somewhere
for file in `ls *.$extension`
      mv $file $i.$extension
      let i=$i+1

usage: jpg
# 3  
Old 12-07-2007
i see. so what's the $1 for? does the shell recognize that as the last characters after the last dot '.' in a filename?

also, i just want it to work for the current directory. so no reason to have a path. i guess you could, but just make it something like '$path = pwd' or something. would that work? i was thinking of using a for loop but this looks much simpler and less lines of code. i thought there would be regex involved or sed or something more complex so that it would only work on a few filetypes (images). i'd like to just type in the command while i'm in the directory i want to change and have it do it without typing in any other commands or options or parameters. what do you think?

btw i use zsh. that shouldn't make any difference right?
# 4  
Old 12-07-2007
You said you wanted the list sorted alphabetically:

for file in $(ls *.$extension | sort); do ...

To answer your questions:
- $1 is a positional parameter. Arguments given to a script will be placed into $1, $2, etc.
- You can certainly work in whatever directory you choose, but "$path" does nothing and "$PATH" is something else entirely. Just leave out the "cd" command to work in the current directory.
- If you don't want to include any other arguments, then simply hard-code the value of $extension. (hard-code? *cough*)

Welcome to the wide world of shell scripting!

Last edited by gus2000; 12-07-2007 at 10:45 PM..
# 5  
Old 12-07-2007
bash: ( *$filetype GLOB is expanded to an alphabetic list )

list=( *.$filetype )
for (( i = 0 ; i < ${#list[*]} ; )) ; do 
    mv ${list[$i]} $((++i)).$filetype

Last edited by reborg; 12-07-2007 at 08:53 PM..
# 6  
Old 12-07-2007
thank you for the great replies. so this is how i think it should go. the logic is there i suppose but the syntax is way off. i'm trying to create this script to work under any conditions (in any directory) and not tamper with anything but. so, i threw in a little regex, and even that is probably off, but it's to help me sleep at night. how does this look to you guys?
regex = '/[jpg]$/'
filetype = '.jpg'
list = (ls | grep $regex)
for (( i = 0 ; i < ${#list[*]} ; i++ )) ; do 
    mv ${list[$i]} $((++i)).$filetype

# 7  
Old 12-11-2007
i tried yours, reborg, and it kinda messed me up a little.

kumi@throne:atlas/images/photos % sudo chmod a+x gallery
kumi@throne:atlas/images/photos % ls
10.jpg  12.jpg  14.jpg  16.jpg  18.jpg  1.jpg   21.jpg  23.jpg  25.jpg  27.jpg  29.jpg  30.jpg  32.jpg  34.jpg  36.jpg  4.jpg  6.jpg  8.jpg  gallery*
11.jpg  13.jpg  15.jpg  17.jpg  19.jpg  20.jpg  22.jpg  24.jpg  26.jpg  28.jpg  2.jpg   31.jpg  33.jpg  35.jpg  3.jpg   5.jpg  7.jpg  9.jpg
kumi@throne:atlas/images/photos % ./gallery 
mv: overwrite `1.jpg', overriding mode 0644? y
mv: cannot move `10.jpg' to `1.jpg': Permission denied
mv: overwrite `2.jpg', overriding mode 0644? 
kumi@throne:atlas/images/photos % sudo ./gallery 
kumi@throne:atlas/images/photos % ls
10.jpg  12.jpg  14.jpg  16.jpg  18.jpg  20.jpg  22.jpg  24.jpg  26.jpg  28.jpg  30.jpg  32.jpg  34.jpg  36.jpg
11.jpg  13.jpg  15.jpg  17.jpg  19.jpg  21.jpg  23.jpg  25.jpg  27.jpg  29.jpg  31.jpg  33.jpg  35.jpg  gallery*

as you can see, i lost 10 photos. why?
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