You may have encountered a situation in which you wanted to specify an argument that started with a hyphen, and your command complained about the improper options that were being used. For example, if grep(1) were used to search a source program for the string --help, you might experience the following under FreeBSD:
$ grep --help tempnam.c
grep: illegal option -- -
usage: grep [-[AB] <num>] [-CEFGLVXHPRSZabchilnqsvwxy]
[-e <expr>] [-f file] [files ...]
$
The problem with this grep(1) command is that the command was confused about how to treat the text --help. The following technique shows how to avoid this little problem:
$ grep -- --help tempnam.c
$
The example shows that grep(1) understood the -- (double hyphen) on the command line to indicate that there were no further options. This permitted grep(1) to understand that --help was the text being searched for in the file tempnam.c.
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