Using grep to recursively search through subdirectories for specific keyword inside specific filename

Question

Im trying to look for the text Elapsed time inside a specific log file names vsim.log. Im not familiar with grep, but after some googling I found that grep -r will allow me to do recursively searches and grep -r "Elapsed time" will do recursive searches for that phrase within all files in my directory. According to this link, I can then do grep -r "Elapsed time" ./vsim* to recursively search through the directories for files starting with vsim and look inside those files for Elapsed time. However, when i tried this i get grep: No match. which i know is not true since I know the files exist there with those keywords. What am i messing up?

Answer 1

Continuing from my comment, you can use find to locate the file vsim.log if you do not know its exact location and then use the -execdir option to find to grep the file for the term Elapsed time, e.g.

find path -type f -name "vsim.log" -execdir grep -H 'Elapsed time' '{}' +

That will return the filename along with the matched text which you can simply parse to isolate the filename if desired. You can process all files that match if you anticipate more than one by feeding the results of the find command into a while read -r loop, e.g.

while read -r match; do
    # process "$match" as desired
    echo "Term 'Elapsed time' found in file ${match%:*}"
done < <(find path -type f -name "vsim.log" -execdir grep -H 'Elapsed time' '{}' +)

Where:

• find is the swiss-army knife for finding files on your system

• path can be any relative or absolute path to search (e.g. $HOME or /home/dorojevets) to search all files in your home directory

• the option -type f tells find to only locate files (see man find for link handling)

• the option -name "foo" tell find to only locate files named foo (wildcards allowed)

• the -exec and -execdir options allow you to execute the command that follows on each file (represented by '{}')

• the grep -H 'Elapsed time' '{}' being the command to execute on each filename

• the + being what tells find it has reached the end of the command (\; used with -exec)

• finally, the ${match%:*} parameter expansion on the variable $match is used to parse the filename from filename:Elapsed time returned by grep -H (the %:* simply being used to trim everything to the first : from the right of $match)

Give that a try and compare the execution time to a recursive grep of the file tree. What you may be missing in this discussion, is that you use find if you know some part of the filename (or file mod time, or set of permissions, etc) that contains the information you need. It can search millions of files in a file tree vastly quicker than you can recursively grep every single file. If you have no clue what file may contain the needed info -- then use grep and just wait...

Answer 2

Try:

grep -r "Elapsed time" * --include vsim.log

Or this answer Use grep --exclude/--include syntax to not grep through certain files.

Answer 3

The following works just in case if you are using Mac:

To search UUID in *.c files recursively under given folder "/home" use the following:

grep -r "UUID" --include "*.c" /home/

To recursively search UUID in all main.c files in multiple projects under current folder use the following:

grep -r "UUID" --include "main.c" .