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expand --help
Usage: expand [OPTION]... [FILE]...
Convert tabs in each FILE to spaces, writing to standard output.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
-i, --initial do not convert tabs after non blanks
-t, --tabs=NUMBER have tabs NUMBER characters apart, not 8
-t, --tabs=LIST use comma separated list of explicit tab positions
--help display this help and exit
--version output version information and exit
$ unexpand --help
Usage: unexpand [OPTION]... [FILE]...
Convert blanks in each FILE to tabs, writing to standard output.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
-a, --all convert all blanks, instead of just initial blanks
--first-only convert only leading sequences of blanks (overrides -a)
-t, --tabs=N have tabs N characters apart instead of 8 (enables -a)
-t, --tabs=LIST use comma separated LIST of tab positions (enables -a)
--help display this help and exit
--version output version information and exit