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2.1.10 Environment

Various environment variables influence how RCS works.

Environment Variable: RCSINIT ¶

Another way to set common options is with the ‘RCSINIT’ environment variable. This is a space-separated list of options. Use ‘\’ (backslash) to escape significant space. For example:

# Set the value; make it available to subsequent commands.
RCSINIT="-q -x/,v -zLT"
export RCSINIT

# Use it (implicitly).
rlog -L foo

This example, in Bourne shell syntax, arranges for RCS commands to operate as if each command-line had prepended ‘-q -x/,v -zLT’ to the rest of the command-line. The effective command-line that rlog sees is thus ‘-q -x/,v -zLT -L foo’.

Environment Variable: 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 the ‘RCS_MEM_LIMIT’ environment variable to a numeric value (measured in kilobytes). An empty value is silently ignored.

As a side effect, specifying the memory limit inhibits fall-back to slower routines. (This env var is mostly intended for testing RCS; normally, you can leave it unset. Probably it will be removed in a future release.)

Environment Variable: TMPDIR ¶

Environment Variable: TMP ¶

Environment Variable: TEMP ¶

Commands sometimes create temporary files, normally in a system-dependent directory, such as /tmp. You can override this directory by specifying another one as the value of one of the environment variables TMPDIR, TMP, or TEMP (checked in that order).

Environment Variable: LOGNAME ¶

Environment Variable: USER ¶

Absent -wlogin, or when login is omitted (see Misc common options), commands check environment variables LOGNAME and USER in that order². If neither of these are set, RCS queries the host for, and uses, your login.