Ubuntu – Grep through subdirectories

bashcommand linegrep

Add a string to a text file from terminal

I've been looking at this thread. The solution (number 2, with ls grep) works perfectly for files called .txt in the current directory. How about if I wanted to search through a directory and the subdirectories?

For example, I have to search through a directory that has many subdirectories, and they have many subdirectories etc.

I'm new to Linux sorry, so I'm not sure if this is the right place

Best Answer

Use the -R (equivalent to --recursive) option to grep.

EDIT: after reading the thread, in the combination ls /mydata | grep txt$ you do not need recursive grep, but recursive ls. You do not grep the files; you grep the output of ls, which happens to be a list of files.

"Recursive ls" is called find :-)

find /mydata -type f | grep txt$

or, better,

find /mydata -type f -name '*.txt'

Related Solutions

Ubuntu – Use a list of words to grep in an other list

I'd ignore grep for this one. It's good for regular expressions but it doesn't look like you really need that here. comm can compare two files and show you intersections. Using your exact examples:

$ comm -12 list.txt output.txt 
a.1
b.1
etc

This is faster than any grep will be but it relies (heavily) on the files being sorted. If they aren't, you can pre-sort them but that will alter the output so it's sorted too.

comm -12 <(sort list.txt) <(sort output.txt)

Alternatively, this answer from iiSeymour will let you do it with grep. The flags ask for an input file and force a fixed-string, full-word search. This won't rely on order but will be based on the output.txt order. Reverse the files if you want them in the order of the list.txt.

$ grep -wFf list.txt output.txt 
a.1
b.1
etc

If your list.txt is really big, you might have to tackle this a little more iteratively and pass each line to grep separately. This will massively increase processing time. In the above you'd be reading output.txt once, but this way you'd read and process it for every list.txt line. It's horrible... But it might be your only choice. On the upside, it does then sort things by the list.txt order.

$ while read line; do grep -wF "$line" output.txt; done < list.txt
a.1
b.1
etc

Ubuntu – How to use grep on all files non-recursively in a directory

In Bash, a glob will not expand into hidden files, so if you want to search all the files in a directory, you need to specify hidden files .* and non-hidden *.

To avoid the "Is a directory" errors, you could use -d skip, but on my system I also get an error grep: .gvfs: Permission denied^†, so I suggest using -s, which hides all error messages.

So the command you are looking for is:

grep -s "string" * .*

If you are searching files in another dir:

grep -s "string" /path/to/dir/{*,.*}

Another option is to use the dotglob shell option, which will make a glob include hidden files.

shopt -s dotglob
grep -s "string" *

For files in another dir:

grep -s "string" /path/to/dir/*

† Someone mentioned that I shouldn't get this error. They may be right - I did some reading but couldn't make heads or tails of it myself.

Best Answer

Related Solutions

Ubuntu – Use a list of words to grep in an other list

Ubuntu – How to use grep on all files non-recursively in a directory

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