File: gawk.info,  Node: OpenVMS Running,  Next: OpenVMS GNV,  Prev: OpenVMS Installation Details,  Up: OpenVMS Installation

B.3.2.4 Running 'gawk' on OpenVMS
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Command-line parsing and quoting conventions are significantly different
on OpenVMS, so examples in this Info file or from other sources often
need minor changes.  They _are_ minor though, and all 'awk' programs
should run correctly.

   Here are a couple of trivial tests:

     $ gawk -- "BEGIN {print ""Hello, World!""}"
     $ gawk -"W" version
     ! could also be -"W version" or "-W version"

Note that uppercase and mixed-case text must be quoted.

   The OpenVMS port of 'gawk' includes a 'DCL'-style interface in
addition to the original shell-style interface (see the help entry for
details).  One side effect of dual command-line parsing is that if there
is only a single parameter (as in the quoted program string), the
command becomes ambiguous.  To work around this, the normally optional
'--' flag is required to force Unix-style parsing rather than 'DCL'
parsing.  If any other dash-type options (or multiple parameters such as
data files to process) are present, there is no ambiguity and '--' can
be omitted.

   The 'exit' value is a Unix-style value and is encoded into an OpenVMS
exit status value when the program exits.

   The OpenVMS severity bits will be set based on the 'exit' value.  A
failure is indicated by 1, and OpenVMS sets the 'ERROR' status.  A fatal
error is indicated by 2, and OpenVMS sets the 'FATAL' status.  All other
values will have the 'SUCCESS' status.  The exit value is encoded to
comply with OpenVMS coding standards and will have the 'C_FACILITY_NO'
of '0x350000' with the constant '0xA000' added to the number shifted
over by 3 bits to make room for the severity codes.

   To extract the actual 'gawk' exit code from the OpenVMS status, use:

     unix_status = (vms_status .and. %x7f8) / 8

A C program that uses 'exec()' to call 'gawk' will get the original
Unix-style exit value.

   OpenVMS reports time values in GMT unless one of the
'SYS$TIMEZONE_RULE' or 'TZ' logical names is set.

   The default search path, when looking for 'awk' program files
specified by the '-f' option, is '"SYS$DISK:[],AWK_LIBRARY:"'.  The
logical name 'AWKPATH' can be used to override this default.  The format
of 'AWKPATH' is a comma-separated list of directory specifications.
When defining it, the value should be quoted so that it retains a single
translation and not a multitranslation 'RMS' searchlist.

   This restriction also applies to running 'gawk' under GNV, as
redirection is always to a DCL command.

   If you are redirecting data to an OpenVMS command or utility, the
current implementation requires setting up an OpenVMS foreign command
that runs a command file before invoking 'gawk'.  (This restriction may
be removed in a future release of 'gawk' on OpenVMS.)

   Without this command file, the input data will also appear prepended
to the output data.

   This also allows simulating POSIX commands that are not found on
OpenVMS or the use of GNV utilities.

   The example below is for 'gawk' redirecting data to the OpenVMS
'sort' command.

     $ sort = "@device:[dir]vms_gawk_sort.com"

   The command file needs to be of the format in the example below.

   The first line inhibits the passed input data from also showing up in
the output.  It must be in the format in the example.

   The next line creates a foreign command that overrides the outer
foreign command which prevents an infinite recursion of command files.

   The next to the last command redirects 'sys$input' to be
'sys$command', in order to pick up the data that is being redirected to
the command.

   The last line runs the actual command.  It must be the last command
as the data redirected from 'gawk' will be read when the command file
ends.

     $!'f$verify(0,0)'
     $ sort := sort
     $ define/user sys$input sys$command:
     $ sort sys$input: sys$output: