Grep - Input File is also the output file

Question

I'm using command line

grep -rI "TEXTSEARCH" . > output.txt

and I get the error/prompt

grep: input file ‘./output.txt’ is also the output

Seems to work successfully but don't want to make extensive searching if this is something to worry about or is that just a regular response?

Why did you tag this with gawk when your whole question is about grep? — Ed Morton, Dec 12 '16 at 23:27

score 4 · Answer 1 · answered Dec 09 '16 at 14:39

-I and . means "all files in the current directory".

As output.txt is created as soon as the command starts

grep -rI "TEXTSEARCH" output.txt > output.txt

happens. So it makes sense.

if "output.txt" is not in the same folder, no issue.

grep -rI "TEXTSEARCH" . > /tmp/output.txt;mv /tmp/output.txt .

1 Answers1