Shell tips & tricks

arg.md

Parse argument from shell command.

• $1: first argument
• ${1:-2}: first argument or fallback to 2

find-text-in-dir.md

Find text in directory

$ 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.

Along with these, --exclude, --include, --exclude-dir flags could be used for efficient searching:

• This will only search through those files which have .c or .h extensions:

  $ grep --include=*.{c,h} -rnw '/path/to/somewhere/' -e "pattern"

• This will exclude searching all the files ending with .o extension:

  $ grep --exclude=*.o -rnw '/path/to/somewhere/' -e "pattern"

• For directories it's possible to exclude a particular directory(ies) through --exclude-dir parameter. For example, this will exclude the dirs dir1/, dir2/ and all of them matching *.dst/:

  $ grep --exclude-dir={dir1,dir2,*.dst} -rnw '/path/to/somewhere/' -e "pattern"

Source: https://stackoverflow.com/a/16957078