---
name: "sdiff"
section: "1"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/sdiff"
---

# sdiff(1)

side-by-side diff

## NAME

**sdiff** – side-by-side diff

## SYNOPSIS

**sdiff** \[**-abdilstHW**\] \[**-I** *regexp*\] \[**-o** *outfile*\] \[**-w** *width*\] *file1* *file2*

**sdiff** **--help**

## 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** **--left-column**

  Only print the left column for identical lines.

- **-o** **--output** *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.

  - **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** **--suppress-common-lines**

  Skip identical lines.

- **-w** **--width** *width*

  Print a maximum of *width* characters on each line. The default is 130 characters.

- **--help**

  Print the usage message and exit.

Options passed to [diff(1)](/diff/1.md) are:

- **-a** **--text**

  Treat *file1* and *file2* as text files.

- **-b** **--ignore-space-change**

  Ignore trailing blank spaces.

- **-d** **--minimal**

  Minimize diff size.

- **-I** **--ignore-matching-lines** *regexp*

  Ignore line changes matching *regexp*. All lines in the change must match *regexp* for the change to be ignored.

- **-i** **--ignore-case**

  Do a case-insensitive comparison.

- **-t** **--expand-tabs**

  Expand tabs to spaces.

- **-W** **--ignore-all-space**

  Ignore all spaces.

- **-B** **--ignore-blank-lines**

  Ignore blank lines.

- **-E** **--ignore-tab-expansion**

  Treat tabs and eight spaces as the same.

- **-H** **--speed-large-files**

  Assume scattered small changes in a large file.

- **--ignore-file-name-case**

  Ignore the case of file names.

- **--no-ignore-file-name-case**

  Do not ignore file name case.

- **--strip-trailing-cr**

  Skip identical lines.

- **--tabsize** *NUM*

  Change the size of tabs (default is 8.)

## 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)](/vi/1.md).

- 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.

The **--help** option exits with a status of 0.

## SEE ALSO

[cmp(1)](/cmp/1.md), [diff(1)](/diff/1.md), [diff3(1)](/diff3/1.md), [vi(1)](/vi/1.md), [re\_format(7)](/re_format/7.md)

## AUTHORS

**sdiff** was written from scratch for the public domain by Ray Lai ⟨*ray@cyth.net*⟩.

## CAVEATS

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.