File: gawk.info,  Node: PC Using,  Next: Cygwin,  Prev: PC Compiling,  Up: PC Installation

B.3.1.3 Using 'gawk' on PC Operating Systems
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Information in this section applies to the MinGW port of 'gawk'.  *Note
Cygwin:: for information about the Cygwin port.

   Under MS-Windows, the MinGW environment supports both the '|&'
operator and TCP/IP networking (*note TCP/IP Networking::).

   The MS-Windows version of 'gawk' searches for program files as
described in *note AWKPATH Variable::.  However, semicolons (rather than
colons) separate elements in the 'AWKPATH' variable.  If 'AWKPATH' is
not set or is empty, then the default search path is
'.;c:/lib/awk;c:/gnu/lib/awk'.

   Under MS-Windows, 'gawk' (and many other text programs) silently
translates end-of-line '\r\n' to '\n' on input and '\n' to '\r\n' on
output.  A special 'BINMODE' variable (c.e.)  allows control over these
translations and is interpreted as follows:

   * If 'BINMODE' is '"r"' or one, then binary mode is set on read
     (i.e., no translations on reads).

   * If 'BINMODE' is '"w"' or two, then binary mode is set on write
     (i.e., no translations on writes).

   * If 'BINMODE' is '"rw"' or '"wr"' or three, binary mode is set for
     both read and write.

   * 'BINMODE=NON-NULL-STRING' is the same as 'BINMODE=3' (i.e., no
     translations on reads or writes).  However, 'gawk' issues a warning
     message if the string is not one of '"rw"' or '"wr"'.

The modes for standard input and standard output are set one time only
(after the command line is read, but before processing any of the 'awk'
program).  Setting 'BINMODE' for standard input or standard output is
accomplished by using an appropriate '-v BINMODE=N' option on the
command line.  'BINMODE' is set at the time a file or pipe is opened and
cannot be changed midstream.

   On POSIX-compatible systems, this variable's value has no effect.
Thus, if you think your program will run on multiple different systems
and that you may need to use 'BINMODE', you should simply set it (in the
program or on the command line) unconditionally, and not worry about the
operating system on which your program is running.

   The name 'BINMODE' was chosen to match 'mawk' (*note Other
Versions::).  'mawk' and 'gawk' handle 'BINMODE' similarly; however,
'mawk' adds a '-W BINMODE=N' option and an environment variable that can
set 'BINMODE', 'RS', and 'ORS'.  The files 'binmode[1-3].awk' (under
'gnu/lib/awk' in some of the prepared binary distributions) have been
chosen to match 'mawk''s '-W BINMODE=N' option.  These can be changed or
discarded; in particular, the setting of 'RS' giving the fewest
"surprises" is open to debate.  'mawk' uses 'RS = "\r\n"' if binary mode
is set on read, which is appropriate for files with the MS-DOS-style
end-of-line.

   To illustrate, the following examples set binary mode on writes for
standard output and other files, and set 'ORS' as the "usual"
MS-DOS-style end-of-line:

     gawk -v BINMODE=2 -v ORS="\r\n" ...

or:

     gawk -v BINMODE=w -f binmode2.awk ...

These give the same result as the '-W BINMODE=2' option in 'mawk'.  The
following changes the record separator to '"\r\n"' and sets binary mode
on reads, but does not affect the mode on standard input:

     gawk -v RS="\r\n" -e "BEGIN { BINMODE = 1 }" ...

or:

     gawk -f binmode1.awk ...

With proper quoting, in the first example the setting of 'RS' can be
moved into the 'BEGIN' rule.