Using ls
 

I have a directory containing .jpg files like this:

I'm trying to write a script to create a photo gallery.

In this directory the files that start with an underscore "_" are thumbnails and the files without the leading underscore are full size pictures.

In the script I'm writing I need to list only the full size pictures, the ones without the leading underscore. It's easy to list only the thumbnails by using:

But for the life of me I can't figure out how to list only the files without the leading underscore.

Any ideas?

Thanks.

LocoMojo

$ ls | grep -v _*.jpg

Hi Ashamril,

Thanks for your reply, but your suggestion didn't work.

I got:

Any other ideas? I tried using ls | cut -c but that doesn't work either.

LocoMojo

Try "ls [^_]*.jpg".

Hello btmiller,

That worked like a charm...thanks!!!

What does that mean? I want to read about it, where would I find information about it in the man pages? Is it regex?

Thanks again!

LocoMojo

You could use the file pattern [^_]*.jpg

i.e. ls [^_].jpg

The "carat" symbol negates the character match if it is the first symbol.

The grep example didn't work because you didn't have a wild card character after the underscore.
ls | '^_.*\.jpg'
There is a difference between the asterisk character in the shell, versus in a regular expression. An asterisk in the shell expands to any character or characters. In a regular expression, it expands to zero or more occurences of the previous character. Because the 'dot' character is used as a wild card in regular expressions, if you want to match the actual character, you need to escape it by preceding it with a backslash.

jschiwal,

Thanks for that.

I learned something new. I didn't know about the different uses of wildcards in the shell and regular expressions.

I've never really gotten into learning about regular expressions. Obviously they're very useful so I should get into learning about it. Know of any good sources of information about regular expressions for beginners?

Thanks again.

LocoMojo

The bash reference may have information on it.

Here is a Regular Expression tutorial on the web: http://www.grymoire.com/Unix/Regular.html

A Linux Focus Article: http://www.linuxfocus.org/English/Ju...article53.html

There is a book called "Linux Shells by Example" which may have the best examples and exercises on Regular Expressions. They are used for VIM, sed, awk and other programs.
http://www.amazon.com/gp/product/013...lance&n=283155

Also, the O'Reilly book "Sed & Awk" has a chapter on Regular Expressions. The 1st Edition is available on the web. If you google for it you may find it.

Here is an example that I have found useful. Suppose that you have downloaded several files in Pan, but because people aren't very original in naming them, you have many that look like: catpic.jpg catpic_copy_2.jpg catpic_copy_3.jpg.

There may be several like that, and some may be duplicates. If there are duplicates, you want to get rid of them.

I highlighted the metacharacter "[[:digit:]]" used. The "${file/_copy_[[:digit:]]/}" expression will expand "catpic_copy_2.jpg" to "catpic.jpg"