retab [ -o|-O output-file | -t|-i input-tab-size | -T|-n output-tab-size | input-file ] ...
Convert a file from one width of tabbing to another. The input file has its tabs converted into spaces according to its input-tab-size and then inserts tabs again according to the output-tab-size and writes to the output file. The output file will look the same as the input when each is viewed with its own tab size, but the tabs and other spacing can be very different.
The parameters are processed in order. As each input file occurs in the parameter list, it is processed according to the nearest proceeding output file and tab sizes. Default in tab size is 8, default out tab size is 4.
If the output tab size is 0, no tabs are written, only spaces.
If no output file is given, new files are written to standard out. If no input file is given, standard input is read.