Should I always use GAWK over AWK?

Question

I see that all features of AWK are included in GAWK, besides using a system that doesn't have GAWK installed, is there ever a good reason I should use AWK versus GAWK? Does AWK have better performance over GAWK?

Answer 1

awk can refer to many things. There's awk-the-standard, and there's many different implementations, one of which is gawk.

Not using implementation-specific features means that you'll have a high(er) chance that your code will run unchanged on other implementations of awk-the-language.

gawk, being one implementation of awk-the-language, claims to conform to awk-the-standard, while adding some extra features.

$ man awk
…
DESCRIPTION
   Gawk is the GNU Project's implementation of the AWK programming
   language.  It conforms to the definition of the language in the
   POSIX 1003.1 Standard.  This version in turn is  based  on  the
   description in The AWK Programming Language, by Aho, Kernighan,
   and Weinberger.  Gawk provides the additional features found in
   the current version of Brian Kernighan's awk and  a  number  of
   GNU-specific extensions.
…

As for speed, using gawk as "plain" awk should make no difference – often, when gawk is installed, awk will just be a symlink to gawk which means they'll be exactly the same program.

However, using gawk-specific features will mean that you'll be locked in to that specific implementation – so if (hypothetically) you'd find a faster implementation, you'd probably have to adapt your script instead of just swapping out the binary. (There may be implementations that are faster, but I don't know of any as I've never had the need to make my awk scripts run faster.)

Personally, I tend to stick to "plain" awk and not use gawk-specific features, but if you don't care about switching to an other implementation, using gawk extensions might make your script easier to write and save you time on that end.

Answer 2

Nowadays the most common implementation of AWK is gawk, and possibly the second most common one is mawk, at least because it's the system AWK on debian.

To quote the output of apt-cache show mawk

Mawk is smaller and much faster than gawk. It has some compile-time limits such as NF = 32767 and sprintf buffer = 1020.

On the side of gawk there are a larger number of well thought extensions and, I think, a better management of errors and better error messages, that are a real bonus when you're debugging a complex script and could be a good reason to use gawk, even if you're not interested in its extensions.

On the other hand, if you have a debugged script, if you don't need a particular extension, if you can live with the builtin limits of mawk (that's a lot of ifs) and you want to squeeze the last bit of performance without leaving the comfort of AWK, then mawk is the way to go.