Shell Programming and Scripting

Hi all,
I amd new in UNIX programming. I have a query.
I need to delete some files (like .dec files) from some folders. I have a list of folders. What will be command for it.
Please help me.

Thanks in Advance.

Something like

Code:

for FOLDER in list-of-folders-seperated-by-spaces
do
    rm "$FOLDER/*.dec"  # for .dec files
done

take care if there are spaces in the names of the folders !

Learn "find" command which can do the job better, according to the situation.

Code:

find . -iname *.dec -ok rm {} \;

or

Code:

find ./fold1 /path/fold2 *.dec -ok rm {} \;

The above will ask about removing particular file... and removes if you ask it to do so.

There is more than one way to do it !!

Deleting files in this way is a common requirement and poorly written scripts to do so are a frequent cause of people coming to grief deleting unexpected files and directories.

A few areas people commonly go wrong: -

With this sort of method: -

Code:

find . -iname *.dec -ok rm {} \;

I have not seen a find run this way I would expect a -exec in there but I have only been scripting a year so this may be valid. But to discuss the method I am familiar with as often seen running in a script: -

Code:

find . -iname *.dec -exec rm {} \;

Using this method a new rm process is kicked off every time the find produces a file to delete, the last cleardown script I wrote clears down over 100,000 files. If we were to kick off a new process for each file found then the job would take forever.

A more efficient way from the process point of view would be: -

Code:

rm -f $(find . -iname *.dec)

This only kicks off the one rm process and the one find process.

To move on to the subject of unintentionally deleting the wrong files: -

Code like the above is very dangerous as the find can start following its way down sub directories and deleting files you had not intended.

This is also a dangerous construct commonly found within a script, although not such a problem in the for loop above: -

Code:

rm "$FOLDER/*.dec"  # for .dec files

No check is made to see if the $FOLDER is a valid directory. If the variable is empty then the command will try to delete files under the root-

Code:

rm /*.dec"

By far the safest approach is to: - That way you have no chance of deleting anything outside of your target directory.

Good luck!