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Options begin with a dash and consist of a single character. GNU-style long options consist of two dashes and a keyword. The keyword can be abbreviated, as long as the abbreviation allows the option to be uniquely identified. If the option takes an argument, then the keyword is either immediately followed by an equals sign (`=') and the argument's value, or the keyword and the argument's value are separated by whitespace. If a particular option with a value is given more than once, it is the last value that counts.
Each long option for gawk has a corresponding
POSIX-style option.
The long and short options are
interchangeable in all contexts.
The options and their meanings are as follows:
-F fs
--field-separator fs
FS variable to fs
(see section Specifying How Fields Are Separated).
-f source-file
--file source-file
awk program is to be found in source-file
instead of in the first non-option argument.
-v var=val
--assign var=val
BEGIN rule
(see section Other Command-Line Arguments).
The `-v' option can only set one variable, but it can be used more than once, setting another variable each time, like this: `awk -v foo=1 -v bar=2 ...'.
Caution: Using `-v' to set the values of the built-in
variables may lead to surprising results. awk will reset the
values of those variables as it needs to, possibly ignoring any
predefined value you may have given.
-mf N
-mr N
awk. They are provided
for compatibility but otherwise ignored by
gawk, since gawk has no predefined limits.
(The Bell Laboratories awk no longer needs these options;
it continues to accept them to avoid breaking old programs.)
-W gawk-opt
gawk-specific options is provided next.
--
This is useful if you have file names that start with `-', or in shell scripts, if you have file names that will be specified by the user that could start with `-'.
The previous list described options mandated by the POSIX standard,
as well as options available in the Bell Laboratories version of awk.
The following list describes gawk-specific options:
-W compat
-W traditional
--compat
--traditional
awk language are disabled, so that gawk behaves just
like the Bell Laboratories research version of Unix awk.
`--traditional' is the preferred form of this option.
See section Extensions in gawk Not in POSIX awk,
which summarizes the extensions. Also see
Downward Compatibility and Debugging.
-W copyright
--copyright
-W copyleft
--copyleft
gawk.
-W dump-variables[=file]
--dump-variables[=file]
gawk prints this
list to a file named `awkvars.out' in the current directory.
Having a list of all the global variables is a good way to look for
typographical errors in your programs.
You would also use this option if you have a large program with a lot of
functions, and you want to be sure that your functions don't
inadvertently use global variables that you meant to be local.
(This is a particularly easy mistake to make with simple variable
names like i, j, and so on.)
-W gen-po
--gen-po
gettext Portable Object file on standard
output for all string constants that have been marked for translation.
See section Internationalization with gawk,
for information about this option.
-W help
-W usage
--help
--usage
gawk accepts and then exit.
-W lint[=fatal]
--lint[=fatal]
awk implementations.
Some warnings are issued when gawk first reads your program. Others
are issued at runtime, as your program executes.
With an optional argument of `fatal',
lint warnings become fatal errors.
This may be drastic but its use will certainly encourage the
development of cleaner awk programs.
-W lint-old
--lint-old
awk from Version 7 Unix
(see section Major Changes Between V7 and SVR3.1).
-W non-decimal-data
--non-decimal-data
Caution: This option can severely break old programs. Use with care.
-W posix
--posix
gawk
extensions (just like `--traditional') and adds the following additional
restrictions:
\x escape sequences are not recognized
(see section 3.2 Escape Sequences).
FS is
equal to a single space
(see section Examining Fields).
func for the keyword function is not
recognized (see section Function Definition Syntax).
FS to be a single tab character
(see section Specifying How Fields Are Separated).
fflush built-in function is not supported
(see section Input/Output Functions).
If you supply both `--traditional' and `--posix' on the
command-line, `--posix' takes precedence. gawk
also issues a warning if both options are supplied.
-W profile[=file]
--profile[=file]
awk programs
(see section Profiling Your awk Programs).
By default, profiles are created in a file named `awkprof.out'.
The optional file argument allows you to specify a different
file name for the profile file.
When run with gawk, the profile is just a "pretty printed" version
of the program. When run with pgawk, the profile contains execution
counts for each statement in the program in the left margin, and function
call counts for each function.
-W re-interval
--re-interval
awk,
gawk does not provide them by default. This prevents old awk
programs from breaking.
-W source program-text
--source program-text
AWKPATH Environment Variable).
-W version
--version
gawk.
This allows you to determine if your copy of gawk is up to date
with respect to whatever the Free Software Foundation is currently
distributing.
It is also useful for bug reports
(see section Reporting Problems and Bugs).
As long as program text has been supplied, any other options are flagged as invalid with a warning message but are otherwise ignored.
In compatibility mode, as a special case, if the value of fs supplied
to the `-F' option is `t', then FS is set to the tab
character ("\t"). This is only true for `--traditional' and not
for `--posix'
(see section Specifying How Fields Are Separated).
The `-f' option may be used more than once on the command-line.
If it is, awk reads its program source from all of the named files, as
if they had been concatenated together into one big file. This is
useful for creating libraries of awk functions. These functions
can be written once and then retrieved from a standard place, instead
of having to be included into each individual program.
(As mentioned in
Function Definition Syntax,
function names must be unique.)
Library functions can still be used, even if the program is entered at the terminal, by specifying `-f /dev/tty'. After typing your program, type Ctrl-d (the end-of-file character) to terminate it. (You may also use `-f -' to read program source from the standard input but then you will not be able to also use the standard input as a source of data.)
Because it is clumsy using the standard awk mechanisms to mix source
file and command-line awk programs, gawk provides the
`--source' option. This does not require you to pre-empt the standard
input for your source code; it allows you to easily mix command-line
and library source code
(see section The AWKPATH Environment Variable).
If no `-f' or `--source' option is specified, then gawk
uses the first non-option command-line argument as the text of the
program source code.
If the environment variable POSIXLY_CORRECT exists,
then gawk behaves in strict POSIX mode, exactly as if
you had supplied the `--posix' command-line option.
Many GNU programs look for this environment variable to turn on
strict POSIX mode. If `--lint' is supplied on the command-line
and gawk turns on POSIX mode because of POSIXLY_CORRECT,
then it issues a warning message indicating that POSIX
mode is in effect.
You would typically set this variable in your shell's startup file.
For a Bourne-compatible shell (such as bash), you would add these
lines to the `.profile' file in your home directory:
POSIXLY_CORRECT=true export POSIXLY_CORRECT |
For a csh compatible
shell,(48)
you would add this line to the `.login' file in your home directory:
setenv POSIXLY_CORRECT true |
Having POSIXLY_CORRECT set is not recommended for daily use,
but it is good for testing the portability of your programs to other
environments.
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