NAME
poke - replaces a byte sequence within a file

SYNOPSIS
poke [ -h[bwl] ] file [ offset [ length ]]

DESCRIPTION
Poke advances offset bytes into file and replaces the next length
bytes with those read from standard input. If unspecified, offset
defaults to zero, and length defaults to the number of bytes read
from standard input.

The -h option causes poke to parse standard input as a hexadecimal
representation of the replacement data. The hexadecimal numbers
should not begin with a "0x" prefix, should have at most eight
digits each, and should be separated by spaces, tabs or newlines.
The number of bytes represented by each hexadecimal number depends
on the digits present, unless a suboption is specified. The
suboptions b, w, and l mask each hexadecimal number parsed to 1, 2,
and 4 bytes, respectively. For example, the number 12345 is parsed
as three bytes (01 23 45) if no suboption is specified, otherwise,
one byte (45) if b, two bytes (23 45) if w, or four bytes (00 01 23
45) if l.

DIAGNOSTICS
Exit status is 0 if successful, 1 if an error was detected, or 2 if
an EOF was detected before length replacement bytes could be read
from standard input. Invalid hexadecimal entry from standard input
is treated as an error, and reported as an "I/O error".

SEE ALSO
peek(1)