correct why in deleting files using find

packets · 03-07-2016, 09:01 AM

I just came across to a site and read that it is not advisable to use the command below.

Quote:

find / -name XXXX -exec rm {} \;

Instead, it should be

Quote:

find / -name XXXX -exec rm {} +

I've been using rm {} \; for years but I am curious and maybe I am doing it wrong.

Is there an explanation what + means in exec?

jpollard · 03-07-2016, 09:21 AM

Man page documentation:

Code:

       -exec command {} +
              This  variant  of the -exec action runs the specified command on
              the selected files, but the command line is built  by  appending
              each  selected file name at the end; the total number of invoca‐
              tions of the command will  be  much  less  than  the  number  of
              matched  files.   The command line is built in much the same way
              that xargs builds its command lines.  Only one instance of  `{}'
              is  allowed  within the command.  The command is executed in the
              starting directory.  If find encounters an error, this can some‐
              times  cause an immediate exit, so some pending commands may not
              be run at all.

The actual better choice might be the "-execdir" option.

grail · 03-07-2016, 09:24 AM

When in doubt, run to the man pages. Try searching for :- -exec command {} +

Phantom Of The Linux · 03-07-2016, 02:50 PM

Code:

find / -name XXXX -exec rm {} \;

This will execute the rm command on each instance of the file and/or directory found in the search criteria.

Whereas,

Code:

find / -name XXXX -exec rm {} +

Will collect a list of filenames and/or directories up to ARG_MAX and then execute the rm command.

IMO, much better and doesn't waste system resources by calling rm each time it finds a match.

MadeInGermany · 03-08-2016, 12:28 PM

For deleting files the -delete option/action is even faster.

Code:

find / -type f -name XXXX -delete

Warning: if not 100% sure what it will do, run -print or -ls first, then -delete!

BW-userx · 03-08-2016, 01:01 PM

...

Quote:

For a machine such as a macbook you won't find much difference in performance
between the two commands. However, if you look at the -exec version you can see a
subtle difference:

Code:

sudo find / -iname ".file-to-delete"  -exec rm {} \;

This means that you will find all those files with name ".file-to-delete". However
this search might return some unwanted false positives. When doing something with
sudo you should be a bit more careful. The advantage of using -exec rm {} is that
you can pass arguments to rm like this:

Code:

sudo find / -iname "*~"  -exec rm -i {} \;

In this example I want to remove those backup files that emacs makes. However that
tilde could be in some obscure file that I don't know about and could be
important. Plus I want to confirm the delete. So I put the option '-i' on the rm
command. This will give me an interactive delete.

Also you can refine the usage of rm to delete directories as well as files:

Code:

find /usr/local/share/ -iname "useless" -exec rm -r {} \;

In brief, the -exec gives you a bit more control over the actual command that
removes the found item. The advantage is that you use one tool to find the files,
another tool to remove them. Also not every version of the find utility has the
-delete option. So better to use each tool for its proper job. This is the unix
philosophy - one tool, one job, use them together to do what you need to do.

MadeInGermany · 03-08-2016, 02:22 PM

Unix philosophy - yes.
GNU philosophy - no.
For example, look at GNU tar's compress options!

Phantom Of The Linux · 03-08-2016, 02:37 PM

Quote:

Originally Posted by packets

Is there an explanation what + means in exec?

I thought the OP wanted an explanation of what the + does in the find syntax.

I guess he wanted to know how to use find to delete files as well.

Anyway, this is how I use find to delete files.

Code:

find <path> -iname "pattern" -exec rm '{}' '+'

The single quotes around the brackets will include files/directories with spaces.

add -type f if you only want files and no directories.

BTW, here's a tip. Before deleting many files and directories with find, do a dry run first. Like so

Code:

find <path> -iname "pattern" '{}' '+'

See what files/directories will be deleted beforehand.