[Linux] How to add a literal tab character in a bash shell?

$'\t'

ex: $ sort -t $'\t'
$ echo -n $'\t'

$ echo -e ' \t ' | hexdump -C
00000000 20 09 20 0a | . .| 00000004

[Linux] How to find all files containing specific text on Linux?

grep -rnw '/path/to/somewhere/' -e 'pattern'

• -r or -R is recursive,
• -n is line number, and
• -w stands for match the whole word.
• -l (lower-case L) can be added to just give the file name of matching files.

P.S. example: to find "if ["

grep -rnw '/path/to/somewhere/' -e 'if \['