The sdiff command merges two files and interactively outputs the results. Its arguments are as follows:
sdiff -o outfile options... from-file to-file
This merges from-file with to-file, with output to outfile. If from-file is a directory and to-file is not, sdiff compares the file in from-file whose file name is that of to-file, and vice versa. from-file and to-file may not both be directories.
sdiff options begin with ‘-’, so normally from-file and to-file may not begin with ‘-’. However, -- as an argument by itself treats the remaining arguments as file names even if they begin with ‘-’. You may not use - as an input file.
sdiff without --output (-o) produces a side-by-side difference. This usage is obsolete; use the --side-by-side (-y) option of diff instead.
An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble.