A number of other environment variables affect gawk’s
behavior, but they are more specialized. Those in the following
list are meant to be used by regular users:
GAWK_MSEC_SLEEP ¶Specifies the interval between connection retries,
in milliseconds. On systems that do not support
the usleep() system call,
the value is rounded up to an integral number of seconds.
GAWK_PERSIST_FILE ¶Specifies the backing file to use for persistent storage
of gawk’s variables and arrays.
See Preserving Data Between Runs.
GAWK_READ_TIMEOUT ¶Specifies the time, in milliseconds, for gawk to
wait for input before returning with an error.
See Reading Input with a Timeout.
GAWK_SOCK_RETRIES ¶Controls the number of times gawk attempts to
retry a two-way TCP/IP (socket) connection before giving up.
See Using gawk for Network Programming.
Note that when nonfatal I/O is enabled (see Enabling Nonfatal Output),
gawk only tries to open a TCP/IP socket once.
PMA_VERBOSITY ¶Controls the verbosity of the persistent memory allocator. See Preserving Data Between Runs.
POSIXLY_CORRECT ¶Causes gawk to switch to POSIX-compatibility
mode, disabling all traditional and GNU extensions.
See Command-Line Options.
The environment variables in the following list are meant
for use by the gawk developers for testing and tuning.
They are subject to change. The variables are:
AWKBUFSIZE ¶This variable only affects gawk on POSIX-compliant systems.
With a value of ‘exact’, gawk uses the size of each input
file as the size of the memory buffer to allocate for I/O. Otherwise,
the value should be a number, and gawk uses that number as
the size of the buffer to allocate. (When this variable is not set,
gawk uses the smaller of the file’s size and the “default”
blocksize, which is usually the filesystem’s I/O blocksize.)
AWK_HASH ¶If this variable exists with a value of ‘gst’, gawk
switches to using the hash function from GNU Smalltalk for
managing arrays.
With a value of ‘fnv1a’, gawk uses the
FNV1-A hash function.
These functions may be marginally faster than the standard function.
AWKREADFUNC ¶If this variable exists, gawk switches to reading source
files one line at a time, instead of reading in blocks. This exists
for debugging problems on filesystems on non-POSIX operating systems
where I/O is performed in records, not in blocks.
GAWK_MSG_SRC ¶If this variable exists, gawk includes the file name
and line number within the gawk source code
from which warning and/or fatal messages
are generated. Its purpose is to help isolate the source of a
message, as there are multiple places that produce the
same warning or error message.
GAWK_LOCALE_DIR ¶Specifies the location of compiled message object files
for gawk itself. This is passed to the bindtextdomain()
function when gawk starts up.
GAWK_NO_DFA ¶If this variable exists, gawk does not use the DFA regexp matcher
for “does it match” kinds of tests. This can cause gawk
to be slower. Its purpose is to help isolate differences between the
two regexp matchers that gawk uses internally. (There aren’t
supposed to be differences, but occasionally theory and practice don’t
coordinate with each other.)
GAWK_STACKSIZE ¶This specifies the amount by which gawk should grow its
internal evaluation stack, when needed.
INT_CHAIN_MAX ¶This specifies intended maximum number of items gawk will maintain on a
hash chain for managing arrays indexed by integers.
STR_CHAIN_MAX ¶This specifies intended maximum number of items gawk will maintain on a
hash chain for managing arrays indexed by strings.
TIDYMEM ¶If this variable exists, gawk uses the mtrace() library
calls from the GNU C library to help track down possible memory leaks.
This cannot be used together with the persistent memory allocator.