The previous section described how
awk program files can be named
on the command line with the `-f' option. In most
implementations, you must supply a precise path name for each program
file, unless the file is in the current directory.
gawk, if the file name supplied to the `-f' option
does not contain a `/', then
gawk searches a list of
directories (called the search path), one by one, looking for a
file with the specified name.
The search path is a string consisting of directory names
separated by colons.
gawk gets its search path from the
AWKPATH environment variable. If that variable does not exist,
gawk uses a default path, which is
`.:/usr/local/share/awk'.(18) (Programs written for use by
system administrators should use an
AWKPATH variable that
does not include the current directory, `.'.)
The search path feature is particularly useful for building up libraries
awk functions. The library files can be placed in a
standard directory that is in the default path, and then specified on
the command line with a short file name. Otherwise, the full file name
would have to be typed for each file.
By using both the `--source' and `-f' options, your command line
awk programs can use facilities in
awk library files.
See section A Library of
Path searching is not done if
gawk is in compatibility mode.
This is true for both `--traditional' and `--posix'.
See section Command Line Options.
Note: if you want files in the current directory to be found, you must include the current directory in the path, either by including `.' explicitly in the path, or by writing a null entry in the path. (A null entry is indicated by starting or ending the path with a colon, or by placing two colons next to each other (`::').) If the current directory is not included in the path, then files cannot be found in the current directory. This path search mechanism is identical to the shell's.
Starting with version 3.0, if
AWKPATH is not defined in the
gawk will place its default search path into
ENVIRON["AWKPATH"]. This makes it easy to determine
the actual search path
gawk will use.
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