Useful for finding files that contain text

Best flags

• -i: ignore case
• -r: recursive (search all files below indicated path)
• -n: indicate line numbers
• -l: just list files
• -I: ignore binary files
• -E: use “extended” regular expressions

# grep -[flags] "text string" path
grep -iIrl ssh-ed25519 ~/.ssh
grep -iIrn ssh-ed25519 ~/.ssh

regular expressions help: https://regexr.com/

Other useful grep flags

• -v: list what doesn’t match
• -w: list whole-word matches
• -F: plain text match (no regex)

Examples

Using grep by itself

search for “searchtext”, ignoring case, ignoring binary files, recurisvely search, with line numbers, in this folder.

grep -Iirn "searchtext" .

Just list filenames

search for “searchtext”, ignoring case, ignoring binary files, recurisvely search, just returning filenames, in this folder.

grep -iIrl "searchtext" .

more complex examples

grep --exclude-dir="**.git**" --exclude-dir="**.ipynb_checkpoint**" --exclude="*.png" --exclude="*.svg" -iIrn "searchtext" .
grep -Iirl --exclude=*.svg --exclude-dir=**anaconda3** --exclude-dir=**Trash** tmux ~/

Using grep in a pipe

find all processes named python

ps aux | grep python

with a specific filetype

grep -Iirl "hello" --include=*.{cc,h} 

with newline

pcregrep -rIn -M "\n#{1} " --include=*.md .

GUI

sudo apt install -y libgtk-3-dev
pip install rummage