[SOLVED] bash script to safely and recursively delete files with no extension

amikoyan · 07-26-2023, 03:34 AM

I am slowly working my way through KN King's 'C Programming - a modern approach'. I use geany as an IDE, which creates an 'executable' file with no extension when I compile each source file e.g. heapsort.c would create a file called heapsort. I create many such files and it is a pain to track them down and remove them. I wish to keep the source files.
I have the following directory structure

Code:

/home/mik/C/knking/ch_[1-9]

So, seems like a job for a bash script. So, I have created clean.sh:

Code:

#!/bin/sh
find . -type f  ! -name "*.*" -delete

which I have placed in the /home/mik/C/knking directory. The idea is it recursively deletes files with no extension in the knking directory and the chapter directories below... and nowhere else.

I am scared to run it 'as is' - I have visions of deleting crucial system files.

I have tested it without the -delete and it finds the correct files.

My questions are: is it safe to use from the knking directory? Is there a better/safer solution?

pan64 · 07-26-2023, 06:14 AM

what do you mean by safe here?
(by the way, it is not a shell script, just a single commend)

michaelk · 07-26-2023, 06:41 AM

The . is a shortcut for current working directory. Use the absolute path and regardless of how the script is run only those files in the desired directory will be deleted. Keep a backup of the source code just in case. A regular user only has read execute permissions to system files so it is unlikely to delete them but it would be possible for other files in your home directory.

MadeInGermany · 07-26-2023, 08:21 AM

Looks good.
Have -print (instead of -delete) and check if the listed things are okay for deletion.

Maybe you can use multiple starting points in find:

Code:

#!/bin/sh
find /home/mik/C/knking/ch_[1-9] -type f  ! -name "*.*" -print

The more criteria you have the safer it becomes (there is an implicit AND)
Say you do not want to delete files created in the last hour:

Code:

#!/bin/sh
find /home/mik/C/knking/ch_[1-9] -type f  ! -name "*.*" -mmin +60 -print

boughtonp · 07-26-2023, 08:28 AM

Quote:

Originally Posted by amikoyan

I use geany as an IDE, which creates an 'executable' file with no extension when I compile each source file e.g. heapsort.c would create a file called heapsort.

Have you checked whether that's configurable? (It is if you call the C compiler directly.)

It would be far safer to set a specific extension so you can target those specific files.

Quote:

I am scared to run it 'as is' - I have visions of deleting crucial system files.

Consider something like this:

Code:

#!/bin/bash

find /specific/path INSERT_FILTER_HERE -print

read -r -p 'Enter "YES" to delete the specified files'
if [ "$REPLY" == "YES" ]
then

find /specific/path INSERT_FILTER_HERE -delete

else
 echo '(no action taken)'
fi

Obviously, the two find commands should be identical except for the final print/delete action.

If you're super paranoid, you could write a self-referencing check that grep the current file for "find" and if the commands differ, error and exit - but it would be simpler to configure your IDE or create a build script that names the files differently.

pan64 · 07-26-2023, 08:49 AM

Quote:

Originally Posted by boughtonp

Have you checked whether that's configurable? (It is if you call the C compiler directly.)

It would be far safer to set a specific extension so you can target those specific files.

Consider something like this:

Code:

#!/bin/bash

find /specific/path INSERT_FILTER_HERE -print

read -r -p 'Enter "YES" to delete the specified files'
if [ "$REPLY" == "YES" ]
then

find /specific/path INSERT_FILTER_HERE -delete

else
 echo '(no action taken)'
fi

Obviously, the two find commands should be identical except for the final print/delete action.

If you're super paranoid, you could write a self-referencing check that grep the current file for "find" and if the commands differ, error and exit - but it would be simpler to configure your IDE or create a build script that names the files differently.

Code:

FIND=( find /specific/path INSERT_FILTER_HERE )
"${FIND[@]}" -print
...
"${FIND[@]}" -delete

boughtonp · 07-26-2023, 09:01 AM

There's no need to quote an entire post that's directly above your reply.

Arrays are certainly an option to reduce maintenance. I didn't use them previously because I was keeping it /bin/sh compatible (as amikoyan's original script was) - then when checking the code before posting, I discovered read's -p is Bash specific and since they had mentioned Bash already, I made the simplest change.

Racho · 07-26-2023, 09:30 AM

You may like this:

Code:

echo > remove_script.sh

while read file; do
    echo rm \"$file\" >> remove_script.sh; 
done < <(find /home/mik/C/knking/ch_[1-9] -type f  ! -name "*.*" -print)

chmod +x remove_script.sh

And then look inside remove_script.sh before running it.

amikoyan · 07-26-2023, 09:46 AM

Quote:

Originally Posted by pan64

what do you mean by safe here?

I mean not to delete anything outside of knking directory and its subdirectories. michaelk's suggestion of changing . to an absolute path should fix that possibility.

Turbocapitalist · 07-26-2023, 09:54 AM

Quote:

Originally Posted by amikoyan

I mean not to delete anything outside of knking directory and its subdirectories. michaelk's suggestion of changing . to an absolute path should fix that possibility.

See #6 above. Run find first with -print and then once you are sure of the pattern with -delete or -delete -print.

amikoyan · 07-26-2023, 10:47 AM

Thanks for everyone's helpful suggestions. I have tried this with success:

Code:

#!/bin/sh


find /home/mik/C/knking/ch_[1-9] -type f  ! -name "*.*" -print

read -r -p 'Enter "YES" to delete the specified files '
if [ "$REPLY" == "YES" ]
then

find /home/mik/C/knking/ch_[1-9] -type f  ! -name "*.*" -delete

else
 echo '(no action taken)'
fi

I will try out some of the other ideas when I have more time - e.g. adding a time filter with something like

Code:

-mmin +60 -print

when I have decided on an optimal time based on my use pattern.

Thank again everyone who took time to answer.

MadeInGermany · 07-26-2023, 12:03 PM

Quote:

Originally Posted by Racho