Re: mawk vs gawk: match() difference -- bug? (correct version)

[arnold]

Hi.

Thanks for the report.

It's not a bug. Gawk accepts additional regexp operators \` and \'. If
you run gawk with --traditional or --posix, you will get the same
output as from mawk.

If you need literal ` or ' in your regexp, use [`] and ['] (or just
don't precede them with backslashes) and then you won't run into the problem.

Also, 4.1.3 is 5 years old; the current version is 5.1.0. I suggest
upgrading, even if you have to build from source; doing so isn't hard.

Thanks!

Arnold

Richard <rgollub@gmx.com> wrote:

>       Find below the difference between gawk and mawk regardinng the match()
> built-in function: mawk reacts as expected whilst gawk does not. Hence
> the question: is it a bug?
>
> <quote>
> $ cat test.awk
>       BEGIN {
>               str = "`abcdefghijklmnopqrstuvwxyz` # rest of string"
>               pat = "^\\`[^\\`]*(\\`|\\\\$)"
>               pos = match(str,  pat)
>               print "str = \"" str "\""
>               print "pat = \"" pat "\""
>               print "pos = " pos
>               print "RSTART = " RSTART
>               print "RLENGTH = " RLENGTH
>               print "substr = \"" substr(str, RSTART, RLENGTH) "\""
>             }
>
> $ sudo update-alternatives --config awk
>       There are 2 choices for the alternative awk (providing /usr/bin/awk).
>
>         Selection    Path            Priority   Status
>       ------------------------------------------------------------
>         0            /usr/bin/gawk    10        auto mode
>         1            /usr/bin/gawk    10        manual mode
>       * 2            /usr/bin/mawk    5         manual mode
>
>       Press <enter> to keep the current choice[*], or type selection number: 1
>       update-alternatives: using /usr/bin/gawk to provide /usr/bin/awk (awk)
> in manual mode
>
> $ awk -Wv
>       GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0)
>       Copyright (C) 1989, 1991-2015 Free Software Foundation.
>
>       This program is free software; you can redistribute it and/or modify
>       it under the terms of the GNU General Public License as published by
>       the Free Software Foundation; either version 3 of the License, or
>       (at your option) any later version.
>
>       This program is distributed in the hope that it will be useful,
>       but WITHOUT ANY WARRANTY; without even the implied warranty of
>       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>       GNU General Public License for more details.
>
>       You should have received a copy of the GNU General Public License
>       along with this program. If not, see http://www.gnu.org/licenses/.
>
> $ awk -f test.awk
>       str = "`abcdefghijklmnopqrstuvwxyz` # rest of string"
>       pat = "^\`[^\`]*(\`|\\$)"
>       pos = 1
>       RSTART = 1
>       RLENGTH = 0
>       substr = ""
>
> $ sudo update-alternatives --config awk
>       There are 2 choices for the alternative awk (providing /usr/bin/awk).
>
>         Selection    Path            Priority   Status
>       ------------------------------------------------------------
>         0            /usr/bin/gawk    10        auto mode
>       * 1            /usr/bin/gawk    10        manual mode
>         2            /usr/bin/mawk    5         manual mode
>
>       Press <enter> to keep the current choice[*], or type selection number: 2
>       update-alternatives: using /usr/bin/mawk to provide /usr/bin/awk (awk)
> in manual mode
> $ awk -Wv
>       mawk 1.3.3 Nov 1996, Copyright (C) Michael D. Brennan
>
>       compiled limits:
>       max NF             32767
>       sprintf buffer      2040
>
> $ awk -f test.awk
>       str = "`abcdefghijklmnopqrstuvwxyz` # rest of string"
>       pat = "^\`[^\`]*(\`|\\$)"
>       pos = 1
>       RSTART = 1
>       RLENGTH = 28
>       substr = "`abcdefghijklmnopqrstuvwxyz`"
> </quote>