Posted by CANbike on Wed, 13 May 2015

[Linux] Remove Files not Containing a Specific String

The following is a solution to delete all files in a directory NOT containing a specific string.

The Problem

There’s a directory containing several files. The files containing a specific keyword should be retained, while files not containing the keyword should be deleted.

The Solution

First thing to use is grep.

grep Options

According to the manual, these are the relevant options to use:

-L, --files-without-match
        Suppress normal output; instead print the name of each input
        file from which no output would normally have been printed. The
        scanning will stop on the first match.

-R, -r, --recursive
        Read all files under each directory, recursively; this is equiv-
        alent to the -d recurse option.

-Z, --null
        Output a zero byte (the ASCII NUL character) instead of the
        character that normally follows a file name. For example, grep
        -lZ outputs a zero byte after each  file name instead of the
        usual newline. This option makes the output unambiguous, even
        in the presence of file names containing unusual characters like
        newlines. This option can be used with commands like find
        -print0, perl -0, sort -z, and xargs -0 to process arbitrary
        file names, even those that contain newline characters.


To find files without the “keyword” use the command,

grep -rL "Key word or phrase" .

Search and Remove

To delete files without the “keyword” use the previous command and pipe the data as arguments to rm,

grep -rL "Key word or phrase" . | xargs rm

A Better Search and Remove

The above method works well for standard filenames, but gives issues with filenames containing spaces, quotes, apostrophes, backslashes, or newlines. A safer way is to terminate input items with a null character so that every character is taken literally by xargs.

grep -rLZ "Key word or phrase" . | xargs -0 rm


Remove files not containing a specific string.png

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