unexpand [ -a ] [ -t tablist ] [ file... ]
SUNWesu
expand copies files (or the standard input) to the standard output, with TAB characters expanded to SPACE characters. BACKSPACE characters are preserved into the output and decrement the column count for TAB calculations. expand is useful for pre-processing character files (before sorting, looking at specific columns, and so forth) that contain TAB characters.
unexpand copies files (or the standard input) to the standard output, putting TAB characters back into the data. By default, only leading SPACE and TAB characters are converted to strings of tabs, but this can be overridden by the -a option (see the OPTIONS section below).
expand options are:
Each tab-stop position N must be an integer value greater than zero, and the list must be in strictly ascending order. This is taken to mean that, from the start of a line of output, tabbing to position N causes the next character output to be in the (N+1)th column position on that line.
In the event of expand having to process a tab character at a position beyond the last of those specified in a multiple tab-stop list, the tab character is replaced by a single space character in the output.
unexpand options are:
Each tab-stop position N must be an integer value greater than zero, and the list must be in strictly ascending order. This is taken to mean that, from the start of a line of output, tabbing to position N will cause the next character output to be in the (N+1)th column position on that line. When the -t option is not specified, the default is the equivalent of specifying -t 8 (except for the interaction with -a, described below).
No space-to-tab character conversions occur for characters at positions beyond the last of those specified in a multiple tab-stop list.
When -t is specified, the presence or absence of the -a option is ignored; conversion will not be limited to the processing of leading blank characters.