Ubuntu – Why does this grep for a string in all sub directories not work

command linedirectorygrep

This is the command that I am trying to run.

grep -r "printf" *.c

I am trying to get all the printf lines from all .c files present in my cwd. As of now, my current directory is Desktop, and I have at least 10-15 .c files in my sub-directories under Desktop, but this command doesn't show any matches at all. So how do I make this work in this case?

Best Answer

If you do:

grep -r "printf" *.c

the shell will expand *.c to all files/directories ending in .c in your current directory, if no such file/directory exists, the pattern will be treated literally (presumably you don't have nullglob set).

As you can see, your current pattern is never going beneath the current directory as you don't have any .c file in the current directory or if there are any, they don't have printf in them, leading to the empty output.

You need to use --include to search in selective files only, and also -r to traverse recursively:

grep -r --include="*.c" "printf" .

The above will search in all .c files for the string (pattern) printf, recursively starting from the current directory.

if you want to follow all symlinks:

grep -R --include="*.c" "printf" .

Related Solutions

Ubuntu – Using shell find all sub-directories that contain certain files

If I understand correctly what you want to do, this is the solution:

#!/bin/sh

USAGE="Usage: $0 dir file1 file2 ... fileN\nto find all subdirectories of dir that contain all the given files.\n"

if [ "$#" == "0" ]; then
    printf "$USAGE"
    exit 1
fi

ARG=""
DIR=$1
shift

while (( "$#" )); do
  ARG="$ARG -exec test -e \"{}/$1\" \; "
  shift
done

cmd="find $DIR -type d $ARG -print"
eval $cmd

What it does is this:

The use find ... -type d to find all subdirectories (including the directory given as first parameter). The test -e command checks if a file exists. So for a given directory we have to check all the files given in the command line: test -e /path/to/directory/file1 test -e /path/to/directory/file2 test -e /path/to/directory/file3 ... The /path/to/directory is {} - a single result of find. Then the find-parameter -exec can be used to check for a single file. To check for all files several -exec test parameters are needed. So while loop build a list of there parameters, then this list is put together in a single command and evaluated.

Have fun ...

Directory – How to Search for Files Recursively into Subdirectories

Try using Find

sudo find . -print | grep -i '.*[.]xml'

Best Answer

Related Solutions

Ubuntu – Using shell find all sub-directories that contain certain files

Directory – How to Search for Files Recursively into Subdirectories

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