grep command – it is used to find pattern/string in the files:
https://www.man7.org/linux/man-pages/man1/grep.1.html
I use this one pretty often:
$ grep -rnie “string” filename.txt
r- recursive – read all the files under each directory
n- prefix each line of output with line number where pattern was found
i – ignore case
e – search for given pattern
another example:
grep -n “YOUR SEARCH STRING” * > output-file
sed command
Stream editor for filtering and transforming text
example to show lines between 11115149 and 11145149 for filename input.
$ sed ‘11115149,11145149!d’ filename.txt