I've read Use grep --exclude/--include syntax to not grep through certain files
but in my CentOS6.4, when I do
grep --exclude=*.cmd ckim * -r I see lots of grepped lines from *.cmd files.
so it seems the exclude option is not working for me.
What is wrong?
of course I can do things like
grep ckim \`find . -name \*.c -print\` but I want to know why the grep doesn't work.
You can quote the pattern:
grep -r --exclude="*.cmd" "ckim" ./ PS. ./ is the current directory
nullglob. --exclude=*.cmd is unlikely to match a single file and would remain as is as an argument. It's the right practice but it doesn't give the solution.
nullglob but shopt says it's off and still works. Am I missing something?nullglob is enabled. Thanks to quoting, any kind of pathname expansion is prevented. I can't believe I really overlooked that part.Use . as pathspec instead of *.
grep -r --exclude \*.cmd ckim . 
* is used. Explicit file arguments are still filtered.
. with -r is more clear and never cause unwanted behaviour of shell-expansion.you could also do something like this
grep -rn ckim * | grep -v '\.cmd' 
something.cmd it will not display that line even if the filename does not contain \.cmd
I see lots of grepped lines from *.cmd files. So it seems the exclude option is not working for me.
There is a shell option called nullglob that controls the expansion of shell patterns when there is no matching file.
So, given the following environment:
sh$ touch f.cmd g.sh sh$ mkdir sub sh$ echo ckim > sub/h.cmd sh$ echo ckim > sub/i.cmd On my system (where nullglob is unset), the following command:
grep --exclude=*.cmd ckim * -r Is expanded ("understood") by the shell as:
grep --exclude=*.cmd ckim f.cmd g.sh sub -r That is, I will recursively (-r) search for the string skim starting with f.cmd, g.sh and sub but excluding any file matching the pattern '*.cmd'.
The result is:
# nullglob is unset sh$ grep --exclude=*.cmd ckim * -r sub/i.sh:ckim BUT if in your environment the option nullglob is set, the same command expands to:
grep ckim f.cmd g.sh sub -r Notice how the whole --exclude=... has disappeared. So the result is:
# nullglob is set sh$ grep --exclude=*.cmd ckim * -r sub/i.sh:ckim sub/h.cmd:ckim An now, for the explanation. When the shell encounters a glob pattern (i.e.: containing * or ? or a few more special characters), it expands it with the matching files. But if there is no matching files, it either let the pattern as it (if nullglob is not set) or replace it with "nothing" (if nullglob is set).
Here the pattern is --include=*.cmd (at whole since there is no space in there). In the unlikely event you have a file matching this pattern it would have been replaced. Otherwise it is either let "as it" or completely removed -- depending on nullglob.
You can easely display, set (-s) or unset (-u) the status of nullglob option of your current bash:
sh$ shopt nullglob nullglob on sh$ shopt -u nullglob sh$ shopt nullglob nullglob off sh$ shopt -s nullglob sh$ shopt nullglob nullglob on The shortest code for multiple files (note the DOT for files ending in '~') is:
grep -lr --exclude=*.{zip,bak,~} "Hello world!" world/* (wrong code) grep -lr --exclude=*{zip,bak,~} "Hello world!" world/* (correct code) ChatGPT can give you the wrong code for this specific case. The dot is not followed by '~', as in nycity.txt~
If you want to exclude certain files to grep from, you should use the -l option.
grep -l --exclude=*.cmd ckim * -r 
patternparameter.