grep.txt

--help                     Print help
--version             -V   Print version information

DISPLAY:
--only-matching       -o   Only print matching part
--line-number         -n   Display line number before each line
--files-with-matches  -l   Print only filenames with matches
--files-without-match -L   Print only filenames without matches
--after-context=num   -A   Print trailing context
--before-context-num  -B   Print leading context
--context-num         -C   Print trailing and leading context
--color=when               Whether to use color (never/always/auto)
                      -H   Always print filename
                      -h   Never print filename
--byte-offset         -b   Display byte offset
--count               -c   Only display count of matches
--quiet, --silent     -q   Don't print output
--no-messages         -s   Don't print error messages for unreadable files
--null                     Print a zero byte after the file name.
--label                    Label to use in place of "(standard input)"

HOW TO MATCH:
--ignore-case         -i   Case insensitive match
--invert-match        -v   Invert pattern match
--extended-regexp     -E   Treat pattern as extended regexp
--fixed-strings       -F   Treat pattern as a string, not a regexp
--basic-regexp        -G   Treat pattern as basic regexp 
--file=file           -f   Read patterns from file
--regexp=pattern      -e   Specify multiple patterns, like '-e p1 -e p2' 
--word-regexp,        -w   Only match if word matches regexp
--line-regexp              Only match if line matches regexp

WHICH FILES TO SEARCH:
--recursive,      -R, -r   Recursively search subdirectories
--text                -a   Treat all files as ASCII
--directories=action  -d   How to treat directories (read/recurse/skip)
--devices=action      -D   How to treat devices (read/recurse/skip)
--exclude pattern          Exclude files matching pattern
--include pattern          Include only files matching pattern
--exclude-dir pattern      Exclude directories matching pattern
--include-dir pattern      Include only dirs matching pattern
                      -O   Follow explicitly listed symlinks
                      -P   Don't follow symlinks
                      -S   Follow symlinks
                      -I   Ignore binary files
--binary              -U   Don't print binary files
--binary-files=value       How to handle binary files

MISC
--bz2decompress        -J  Decompress with bzip2 first
--lzma                 -M  Decompress with lzma first
--xz                   -X  Decompress with xz first
--decompress           -Z  Decompress with gunzip first
--max-count num        -m  Stop reading the file after num matches
--mmap                     Use mmap for performance
--null-data            -z  Use zero byte instead of newline for input/output
--line-buffered            Force output to be line buffered
                       -y  Obsolete