grep after grep : No such file or directory

Question

To create a test file contains blanks in the filename first:

vim  "/tmp/it is a test.txt"
bash  escape

Search with grep:

grep    -lr   'bash'  /tmp
/tmp/it is a test.txt

I want to grep command after the grep:

grep    -lr   'bash'  /tmp  | xargs grep  escape
grep: /tmp/it: No such file or directory
grep: is: No such file or directory
grep: a: No such file or directory
grep: test.txt: No such file or directory

So i add -0 in xargs:

grep    -lr   'bash'  /tmp | xargs -0 grep  escape
grep: /tmp/it is a test.txt
: No such file or directory

I find the reason:

grep    -lr   'bash'  /tmp | xargs -0 
grep: /tmp/it is a test.txt
#a blank line at the bottom

xargs -0 add a blank line!
How can suppress the output : No such file or directory ?

Answer 1

As you may have guessed, the first version you tried

grep -lr 'bash' /tmp | xargs grep escape

failed because xargs assumes arguments taken from standard input are delimited by:

space, tab, newline and end-of-file.

You were on the good track by adding the -0 CLI option:

grep -lr 'bash' /tmp | xargs -0 grep escape

But to make it fully working, you'll also need to ensure that xargs 's input is indeed delimited by NUL characters.

Hence the following command that relies on tr :

grep -lr 'bash' /tmp | tr '\n' '\0' | xargs -0 grep escape

Alternatively, a better solution amounts to directly using grep 's --null CLI option:

grep -lr --null 'bash' /tmp | xargs -0 grep escape

or more concisely:

As an aside

I find the reason:
xargs -0 add a blank line!

To explain this further:

xargs -0 alone amounts to xargs -0 echo , and because of -0 , xargs sees the final newline printed by grep (included as you didn't use the --null CLI option) as a character that is part of the filename… which is then printed by echo .

Answer 2

grep has the option -s or --no-messages to suppress error messages about nonexistent or unreadable files.