.\" $OpenBSD: sdiff.1,v 1.19 2017/10/17 22:47:58 schwarze Exp $
.\"
.\" Written by Raymond Lai <ray@cyth.net>.
.\" Public domain.
.\"
.Dd $Mdocdate: October 17 2017 $
.Dt SDIFF 1
.Os
.Sh NAME
.Nm sdiff
.Nd side-by-side diff
.Sh SYNOPSIS
.Nm
.Op Fl abdilstW
.Op Fl I Ar regexp
.Op Fl o Ar outfile
.Op Fl w Ar width
.Ar file1
.Ar file2
.Sh DESCRIPTION
.Nm
displays two files side by side,
with any differences between the two highlighted as follows:
new lines are marked with
.Sq > ;
deleted lines are marked with
.Sq < ;
and changed lines are marked with
.Sq | .
.Pp
.Nm
can also be used to interactively merge two files,
prompting at each set of differences.
See the
.Fl o
option for an explanation.
.Pp
The options are:
.Bl -tag -width Ds
.It Fl l
Only print the left column for identical lines.
.It Fl o Ar outfile
Interactively merge
.Ar file1
and
.Ar file2
into
.Ar outfile .
In this mode, the user is prompted for each set of differences.
See
.Ev EDITOR
and
.Ev VISUAL ,
below,
for details of which editor, if any, is invoked.
.Pp
The commands are as follows:
.Bl -tag -width Ds
.It Cm l | 1
Choose left set of diffs.
.It Cm r | 2
Choose right set of diffs.
.It Cm s
Silent mode \(en identical lines are not printed.
.It Cm v
Verbose mode \(en identical lines are printed.
.It Cm e
Start editing an empty file, which will be merged into
.Ar outfile
upon exiting the editor.
.It Cm e Cm l
Start editing file with left set of diffs.
.It Cm e Cm r
Start editing file with right set of diffs.
.It Cm e Cm b
Start editing file with both sets of diffs.
.It Cm q
Quit
.Nm .
.El
.It Fl s
Skip identical lines.
.It Fl w Ar width
Print a maximum of
.Ar width
characters on each line.
The default is 130 characters.
.El
.Pp
Options passed to
.Xr diff 1
are:
.Bl -tag -width Ds
.It Fl a
Treat
.Ar file1
and
.Ar file2
as text files.
.It Fl b
Ignore trailing blank spaces.
.It Fl d
Minimize diff size.
.It Fl I Ar regexp
Ignore line changes matching
.Ar regexp .
All lines in the change must match
.Ar regexp
for the change to be ignored.
.It Fl i
Do a case-insensitive comparison.
.It Fl t
Expand tabs to spaces.
.It Fl W
Ignore all spaces
(the
.Fl w
flag is passed to
.Xr diff 1 ) .
.El
.Sh ENVIRONMENT
.Bl -tag -width Ds
.It Ev EDITOR , VISUAL
Specifies an editor to use with the
.Fl o
option.
If both
.Ev EDITOR
and
.Ev VISUAL
are set,
.Ev VISUAL
takes precedence.
If neither
.Ev EDITOR
nor
.Ev VISUAL
are set,
the default is
.Xr vi 1 .
.It Ev TMPDIR
Specifies a directory for temporary files to be created.
The default is
.Pa /tmp .
.El
.Sh EXIT STATUS
The
.Nm
utility exits with one of the following values:
.Pp
.Bl -tag -width Ds -offset indent -compact
.It 0
No differences were found.
.It 1
Differences were found.
.It \*(Gt1
An error occurred.
.El
.Sh SEE ALSO
.Xr cmp 1 ,
.Xr diff 1 ,
.Xr diff3 1 ,
.Xr vi 1 ,
.Xr re_format 7
.Sh HISTORY
.Nm
has been available since
.Ox 3.9 .
.Sh AUTHORS
.Nm
was written from scratch for the public domain by
.An Ray Lai Aq Mt ray@cyth.net .
.Sh CAVEATS
Although undocumented,
.Nm
supports most long options supported by GNU sdiff,
though some require GNU diff.
.Pp
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.
.Sh BUGS
.Nm
may not work with binary data.