Grep word within a file then copy the file

Question

I have a collection of files ( *.zip, *.txt, *.tar.gz, *.doc, ...etc ). These files reside within a path. I want to find all the files ( *.txt), then copy, only, the text files that contain specific words ( e.g LINUX/UNIX).

I ran the following:

find . -name "*.txt" | grep 'LINUX/UNIX'

This command was able to find all the text files, then "grep" filtered the resultant text files by listing only the text files that contain 'LINUX/UNIX'.

How can I copy these final files (i.e. the text files that contain 'LINUX/UNIX') to a specific path of choice?

I tried to apply xargs

find . -name "*.txt" | grep 'LINUX/UNIX' | xargs cp <to a path>

But it didn't work

Solution 1

Try:

grep -rl --null --include '*.txt' LINUX/UNIX . | xargs -0r cp -t /path/to/dest

Because this command uses NUL-separation, it is safe for all file names including those with difficult names that include blanks, tabs, or even newlines.

The above requires GNU cp. For MacOS/FreeBSD, try:

grep -rl --null --include '*.txt' LINUX/UNIX . | xargs -0 sh -c 'cp "$@" /path/to/dest' sh

How it works:

1. grep options and arguments

   • -r tells grep to search recursively through the directory structure. (On FreeBSD, -r will follow symlinks into directories. This is not true of either OS/X or recent versions of GNU grep.)

   • --include '*.txt' tells grep to only return files whose names match the glob *.txt (including hidden ones like .foo.txt or .txt).

   • -l tells grep to only return the names of matching files, not the match itself.

   • --null tells grep to use NUL characters to separate the file names. (--null is supported by grep under GNU/Linux, MacOS and FreeBSD but not OpenBSD.)

   • LINUX/UNIX tells grep to look only for files whose contents include the regex LINUX/UNIX

   • . search in the current directory. You can omit it in recent versions of GNU grep, but then you'd need to pass a -- option terminator to cp to guard against file names that start with -.

2. xargs options and arguments

   • -0 tells xargs to expect NUL-separated input.

   • -r tells xargs not to run the command unless at least one file was found. (This option is not needed on either BSD or OSX and is not compatible with OSX's xargs.)

   • cp -t /path/to/dest copies the directories to the target directory. (-t requires GNU cp.)

Solution 2

More portably (POSIX features only):

find . -type f -name '*.txt' -exec grep -q LINUX/UNIX {} \; -exec cp {} /path/to/dest \;

Solution 3

The following sh/Bash one liner is another method, though will only work in the current directory, and doesn't recurse:

for f in ./*.txt; do if grep -l 'LINUX/UNIX' "$f"; then cp "$f" /path/to/dest/; fi; done

The -l option to grep will print a list of the files which are being copied, though you could use -q if you don't want to see anything on the screen.

Comments

[Edward Falk]

For Mac OS X, and probably BSD, you'll want to use --null instead of -Z. Also, I think cp -t is Linux-only.

[John1024]

@EdwardFalk Good point. Thanks. I updated to use --null and added a version for BSD/OSX that does not use cp -t.

[John1024]

@StéphaneChazelas Thank you for the improvements.

[Kusalananda]

OpenBSD grep does not have --null.

[John1024]

@Kusalananda Thanks. Answer updated to note that OpenBSD does not support --null.

[Michal Przybylowicz]

It should be noted here that some grep colorize the output (in other words is puts additional characters into the name of the file). To silence color character use --color=never.

[John1024]

@MichalPrzybylowicz That is a good point. Sometimes, a grep alias is used to turn color on. Such aliases should use --color=auto rather than --color=always. With --color=auto, grep will only colorize if the output is going to a terminal (as opposed to, say, a pipeline as is our case here).