---
name: "rcsmerge"
section: "1"
platform: "linux"
package: "rcs"
version: "5.10.1-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "openbsd"]
url: "https://new.carta.tech/rcsmerge"
---

# rcsmerge(1)

merge RCS revisions

## NAME

rcsmerge - merge RCS revisions

## SYNOPSIS

**rcsmerge** \[*options*\] *file*

## DESCRIPTION

**rcsmerge** incorporates the changes between two revisions of an RCS file into the corresponding working file.

Filenames matching an RCS suffix denote RCS files; all others denote working files. Names are paired as explained in [**ci**(1)](/ci/1.md).

At least one revision must be specified with one of the options described below, usually **-r**. At most two revisions may be specified. If only one revision is specified, the latest revision on the default branch (normally the highest branch on the trunk) is assumed for the second revision. Revisions may be specified numerically or symbolically.

**rcsmerge** prints a warning if there are overlaps, and delimits the overlapping regions as explained in [**merge**(1)](/merge/1.md). The command is useful for incorporating changes into a checked-out revision.

## OPTIONS

- **-A**

  Output conflicts using the **-A** style of [**diff3**(1)](/diff3/1.md), if supported by **diff3**. This merges all changes leading from *file2* to *file3* into *file1*, and generates the most verbose output.

- **-E**, **-e**

  These options specify conflict styles that generate less information than **-A**. See [**diff3**(1)](/diff3/1.md) for details. The default is **-E**. With **-e**, **rcsmerge** does not warn about conflicts.

- **-k***subst*

  Use *subst* style keyword substitution. See [**co**(1)](/co/1.md) for details. For example, **-kk -r1.1 -r1.2** ignores differences in keyword values when merging the changes from **1.1** to **1.2**. It normally does not make sense to merge binary files as if they were text, so **rcsmerge** refuses to merge files if **-kb** expansion is used.

- **-p**\[*rev*\]

  Send the result to standard output instead of overwriting the working file.

- **-q**\[*rev*\]

  Run quietly; do not print diagnostics.

- **-r**\[*rev*\]

  Merge with respect to revision *rev*. Here an empty *rev* stands for the latest revision on the default branch, normally the head.

- **-T**

  This option has no effect; it is present for compatibility with other RCS commands.

- **-V**

  Print RCS's version number.

- **-V***n*

  Emulate RCS version *n*. See [**co**(1)](/co/1.md) for details.

- **-x***suffixes*

  Use *suffixes* to characterize RCS files. See [**ci**(1)](/ci/1.md) for details.

- **-z***zone*

  Use *zone* as the time zone for keyword substitution. See [**co**(1)](/co/1.md) for details.

## EXAMPLES

Suppose you have released revision 2.8 of **f.c**. Assume furthermore that after you complete an unreleased revision 3.4, you receive updates to release 2.8 from someone else. To combine the updates to 2.8 and your changes between 2.8 and 3.4, put the updates to 2.8 into file f.c and execute

    **rcsmerge  -p  -r2.8  -r3.4  f.c  \>f.merged.c**

Then examine **f.merged.c**. Alternatively, if you want to save the updates to 2.8 in the RCS file, check them in as revision 2.8.1.1 and execute **co -j**:

    **ci  -r2.8.1.1  f.c**\
     **co  -r3.4  -j2.8:2.8.1.1  f.c**

As another example, the following command undoes the changes between revision 2.4 and 2.8 in your currently checked out revision in **f.c**.

    **rcsmerge  -r2.8  -r2.4  f.c**

Note the order of the arguments, and that **f.c** will be overwritten.

## ENVIRONMENT

- **RCSINIT**

  Options prepended to the argument list, separated by spaces. A backslash escapes spaces within an option. The **RCSINIT** options are prepended to the argument lists of most RCS commands. Useful **RCSINIT** options include **-q**, **-V**, **-x**, and **-z**.

- **RCS\_MEM\_LIMIT**

  Normally, for speed, commands either memory map or copy into memory the RCS file if its size is less than the *memory-limit*, currently defaulting to \`\`unlimited''. Otherwise (or if the initially-tried speedy ways fail), the commands fall back to using standard i/o routines. You can adjust the memory limit by setting **RCS\_MEM\_LIMIT** to a numeric value *lim* (measured in kilobytes). An empty value is silently ignored. As a side effect, specifying **RCS\_MEM\_LIMIT** inhibits fall-back to slower routines.

- **TMPDIR**

  Name of the temporary directory. If not set, the environment variables **TMP** and **TEMP** are inspected instead and the first value found is taken; if none of them are set, a host-dependent default is used, typically **/tmp**.

## DIAGNOSTICS

Exit status is 0 for no overlaps, 1 for some overlaps, 2 for trouble.

## IDENTIFICATION

Author: Walter F. Tichy.\
 Manual Page Revision: 5.10.1; Release Date: 2022-02-03.\
 Copyright © 2010-2022 Thien-Thi Nguyen.\
 Copyright © 1990, 1991, 1992, 1993, 1994, 1995 Paul Eggert.\
 Copyright © 1982, 1988, 1989 Walter F. Tichy.\

## SEE ALSO

[**ci**(1)](/ci/1.md), [**co**(1)](/co/1.md), [**ident**(1)](/ident/1.md), [**merge**(1)](/merge/1.md), [**rcs**(1)](/rcs/1.md), [**rcsdiff**(1)](/rcsdiff/1.md), [**rlog**(1)](/rlog/1.md), [**rcsfile**(5)](/rcsfile/5.md).

Walter F. Tichy, RCS--A System for Version Control, *Software--Practice & Experience* **15**, 7 (July 1985), 637-654.

The full documentation for RCS is maintained as a Texinfo manual. If the [**info**(1)](/info/1.md) and RCS programs are properly installed at your site, the command

-

  **info rcs**

should give you access to the complete manual. Additionally, the RCS homepage:

-

  **http://www.gnu.org/software/rcs/**

has news and links to the latest release, development site, etc.