Q: What is smenu?

A: smenu is a selection tool that acts as a filter that takes 'words'
   from the standard input or a file and presents them on the screen in
   various arrangements in a scrolling window.

   A cursor that you can easily move allows you to select one or more
   of them.

   The selected 'words' are printed on the standard output.
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Q: Why smenu tells me: "The length of a 'word' has reached the limit of
   512 characters." but there is no such 'word' in my entry?

A: It is likely that you have an unbalanced single or double quotation
   mark somewhere. smenu uses quotation marks to be able to have spaces
   in 'words', and quotation marks that are not used as delimiters must
   be protected.

   You can use something like: sed -e "s/'/\\\'/g" -e 's/"/\\"/g' to
   pre-process the input in such a case.

   Another solution is to ask smenu to treat quotation marks as normal
   characters by using the -Q|-ignore_quotes option.
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Q: Why does smenu -C... no longer work?

A: smenu uses a new system of options based on the notion of contexts. The
   -C parameter is only valid in the "Columns" context as indicated in the
   error message.

   The string '[-c|-col|-col_mode|-column>Columns]' that is printed
   in the error message indicates that to switch to "Columns" mode
   must use the -c parameter or its alternatives.

   In this case the correct command line should contain something like:
   smenu -c -C...
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Q: How to preserve the original alignment of the columns?

A: smenu merges multiple occurrences of word delimiters (' ' in the
   example below) and so the original alignment of columns is lost.
   One way to limit this loss is to replace the delimiter with a character
   that does not appear in the input and is not a delimiter, we will use
   '!' in the example, and tell smenu to replace it with a space with the
   -S option.

   Example of a session using the free command:

   $ free
                  total        used        free      shared  buff/cache   available
   Mem:            23Gi       4,3Gi       1,6Gi       118Mi        18Gi        19Gi
   Swap:          2,0Gi       0,0Ki       2,0Gi

   $ free -h | smenu -c
   total used  free  shared buff/cache available
   Mem:  23Gi  4,3Gi 1,6Gi  118Mi      18Gi      19Gi
   Swap: 2,0Gi 0,0Ki 2,0Gi

   $ free -h | sed -e 's/ /!/g' -e 's/!\([^!]\)/ \1/g'
   !!!!!!!!!!!!!! total!!!!!!! used!!!!!!! free!!!!! shared! buff/cache!! available
   Mem:!!!!!!!!!!! 23Gi!!!!!! 4,3Gi!!!!!! 1,6Gi!!!!!! 120Mi!!!!!!! 18Gi!!!!!!! 19Gi
   Swap:!!!!!!!!! 2,0Gi!!!!!! 0,0Ki!!!!!! 2,0Gi

   $ free -h | sed -e 's/ /!/g' -e 's/!\([^!]\)/ \1/g' | smenu -c -S'/!/ /g'
   ############### total        used        free        shared       buff/cache   available
   Mem:            23Gi         4,3Gi       1,6Gi       118Mi        18Gi         19Gi
   Swap:           2,0Gi        0,0Ki       2,0Gi

   Where ############### is the smenu cursor.