The following table summarizes the common extensions supported
by gawk, Brian Kernighan’s awk, and mawk,
the three most widely used freely available versions of awk
(see Other Freely Available awk Implementations).
| Feature | BWK awk | mawk | gawk | Now standard |
|---|---|---|---|---|
** and **= operators | X | X | ||
| ‘\x’ escape sequence | X | X | X | |
| ‘\u’ escape sequence | X | X | ||
| /dev/stdin special file | X | X | X | |
| /dev/stdout special file | X | X | X | |
| /dev/stderr special file | X | X | X | |
BINMODE variable | X | X | ||
| CSV support | X | X | ||
FS as null string | X | X | X | |
delete without subscript | X | X | X | X |
fflush() function | X | X | X | X |
func keyword | X | X | ||
length() of an array | X | X | X | |
nextfile statement | X | X | X | X |
RS as regexp | X | X | X | |
| Time-related functions | X | X |