processes the named files or the standard input writing the standard output with tabs changed into blanks. 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, etc.) that contain tabs.
If a single tabstop argument is given, then tabs are set tabstop spaces apart instead of the default 8. If multiple tabstops are given then the tabs are set at those specific columns.
unexpand puts tabs back into the data from the standard input or the named files and writes the result on the standard output.
Option (with unexpand only):
By default, only leading blanks and tabs are reconverted to maximal strings of tabs. If the -a option is given, then tabs are inserted whenever they would compress the resultant file by replacing two or more characters.