print lines matching a pattern

-i, --ignore-case
       Ignore case distinctions in both the PATTERN and the input files.  (-i is specified by POSIX.)

-v, --invert-match
       Invert the sense of matching, to select non-matching lines.  (-v is specified by POSIX.)

-m NUM, --max-count=NUM
       Stop reading a file after NUM matching lines.  If the input is standard input from a regular file,
       and NUM matching lines are output, grep ensures that the standard  input  is  positioned  to  just
       after the last matching line before exiting, regardless of the presence of trailing context lines.
       This enables a calling process to resume a search.  When grep stops after NUM matching  lines,  it
       outputs  any  trailing  context  lines.  When the -c or --count option is also used, grep does not
       output a count greater than NUM.  When the -v or --invert-match option is also  used,  grep  stops
       after outputting NUM non-matching lines.

Context Line Control
    -A NUM, --after-context=NUM
           Print NUM lines of trailing context after matching  lines.   Places  a  line  containing  a  group
           separator  (--) between contiguous groups of matches.  With the -o or --only-matching option, this
           has no effect and a warning is given.

grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus
(-) is given as file name) for lines containing a match to the given PATTERN.  By  default,  grep  prints
the matching lines.