To search through text you can use the grep command. It searches files and returns the lines of the file that match a certain string.

The command has the following format:

grep [options] pattern [file]

 

 

Here are some of the useful options I use:

Option	Description
-i	match case insensitive
-n	Include line number of match in output
-r	Search recursively through directories
-F	treat regex litteraly
-m	Specify the maximum number of matches outputed
-H / -h	Include filename / Do not include filename
-A	Specify number of trailing lines after match
-B	Specify number of leading lines before match
-o	Only output the matched word, not the whole line
-l	Output only the names of files containing match
--colour	highlight the matched keyword in the output line

 

Examples

You can also search multiple files eg. all files ending with ‘.log’:

grep "error" "*.log"

And specify multiple patterns:

grep "error|warning" "*.log"

Let’s make some example commands

Highlight the matched word, specify file name and line number and search case insensitively:

grep --colour -Hni "error" "file.txt"

Recursively search in a specified directory

grep -r "error" ./directory

Search all files in current directory with .log extension. Highlight output, maximum number of matches 2, print 1 leading and 1 trailing line

grep --colour -m2 -A1 -B1 "error" "*.log"

Search through directory and only specify name of file containing the match

grep -rl "searchString" /path

 

Aight, go search!