SDIFF(1) | General Commands Manual | SDIFF(1)

# NAME

`sdiff` — side-by-side diff

# SYNOPSIS

`sdiff` | [`-abdilstW`] [`-I` regexp] [`-o` outfile] [`-w` width] file1 file2

# DESCRIPTION

`sdiff` displays two files side by side, with any differences between the two highlighted as follows: new lines are marked with ‘>’; deleted lines are marked with ‘<’; and changed lines are marked with ‘|’.

`sdiff` can also be used to interactively merge two files, prompting at each set of differences. See the `-o` option for an explanation.

The options are:

`-l`
  Only print the left column for identical lines.
`-o` outfile
  Interactively merge file1 and file2 into outfile. In this mode, the user is prompted for each set of differences. See `EDITOR` and `VISUAL`, below, for details of which editor, if any, is invoked.

  The commands are as follows:

  `l` | `1`
    Choose left set of diffs.
  `r` | `2`
    Choose right set of diffs.
  `b l` | `b 1`
    Choose both, left set of diffs first.
  `b r` | `b 2`
    Choose both, right set of diffs first.
  `s`
    Silent mode – identical lines are not printed.
  `v`
    Verbose mode – identical lines are printed.
  `e`
    Start editing an empty file, which will be merged into outfile upon exiting the editor.
  `e` `l`
    Start editing file with left set of diffs.
  `e` `r`
    Start editing file with right set of diffs.
  `e` `b`
    Start editing file with both sets of diffs.
  `q`
    Quit `sdiff`.
`-s`
  Skip identical lines.
`-w` width
  Print a maximum of width characters on each line. The default is 130 characters.

Options passed to diff(1) are:

`-a`
  Treat file1 and file2 as text files.
`-b`
  Ignore trailing blank spaces.
`-d`
  Minimize diff size.
`-I` regexp
  Ignore line changes matching regexp. All lines in the change must match regexp for the change to be ignored.
`-i`
  Do a case-insensitive comparison.
`-t`
  Expand tabs to spaces.
`-W`
  Ignore all spaces (the `-w` flag is passed to diff(1)).

# ENVIRONMENT

`EDITOR`, `VISUAL`
  Specifies an editor to use with the `-o` option. If both `EDITOR` and `VISUAL` are set, `VISUAL` takes precedence. If neither `EDITOR` nor `VISUAL` are set, the default is vi(1).
`TMPDIR`
  Specifies a directory for temporary files to be created. The default is /tmp.

# EXIT STATUS

The `sdiff` utility exits with one of the following values:

0
  No differences were found.
1
  Differences were found.
>1
  An error occurred.

# SEE ALSO

cmp(1), diff(1), diff3(1), vi(1), re_format(7)

# HISTORY

The `sdiff` command first appeared in AT&T System III UNIX and was reimplemented for OpenBSD 3.9.

# AUTHORS

`sdiff` was written from scratch for the public domain by Ray Lai <ray@cyth.net>.

# CAVEATS

Although undocumented, `sdiff` supports most long options supported by GNU sdiff, though some require GNU diff.

Tabs are treated as anywhere from one to eight characters wide, depending on the current column. Terminals that treat tabs as eight characters wide will look best.

# BUGS

`sdiff` may not work with binary data.

February 26, 2025 | Debian