gawk: Command-line directories

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1 4.13 Directories on the Command Line
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1 According to the POSIX standard, files named on the 'awk' command line
1 must be text files; it is a fatal error if they are not.  Most versions
1 of 'awk' treat a directory on the command line as a fatal error.
1 
1    By default, 'gawk' produces a warning for a directory on the command
1 line, but otherwise ignores it.  This makes it easier to use shell
1 wildcards with your 'awk' program:
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1      $ gawk -f whizprog.awk *        Directories could kill this program
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1    If either of the '--posix' or '--traditional' options is given, then
1 'gawk' reverts to treating a directory on the command line as a fatal
1 error.
1 
1    ⇒Extension Sample Readdir for a way to treat directories as
1 usable data from an 'awk' program.
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