speed up grep

how to speed up the grep command?

• drop the -i flag if not need
• use the -F flag for a fixed string
• disable NLS with LANG=C or LC_ALL=C
• set a max number of matches with the -m flag

notice

• egrep == grep -E
• fgrep == grep -F

• https://stackoverflow.com/questions/13913014/grepping-a-huge-file-80gb-any-way-to-speed-it-up