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Subsections

• Synopsis
• Description
• Options
• Notes
• Diagnostics
• Examples
• Bugs
• See also
• Author

ao

AIPS++ source code checkout utility.

Synopsis

ao [

options for

co] file1 [file2 ...]

Description

ao checks out source files from the AIPS++ master RCS repository into the current directory. It is a front-end for the RCS co command.

ao assumes that you are working within a private directory tree which shadows that of the AIPS++ master source code tree, see mktree (p). The filename arguments specified to ao must be simple filenames without path except that an initial RCS/ will be explicitly stripped off, as will any RCS ,v suffix. ao determines the corresponding master directory from the current working directory.

ao checks out the source file by executing $MSTRETCD/ao_master, where $AIPSMSTR is expected to be NFS mounted from the AIPS++ master host (see §1.1.4). Programmers who have an account on the AIPS++ master host, aips2.nrao.edu, may instead use a related utility, rao (p), which invokes ao remotely on the master host via ssh.

Options

ao does not itself interpret any options but does recognize several which it passes to co.

-I | -l | -r# | -u#

These options are passed directly to co, check the manual page for co for an explanation. Note that no version number may be specified for the -l option, and that a -r option with revision number may not be used together with -l. All other co options are defeated.

Note that the -u option may be used to unlock a checked out file without replacement.

Notes

• The RCS co command must have write permission on the version file in order to check it out of the master repository. The file ownership is defined by the owner of $MSTRETCD/ao_master (aips2adm). This script must have the setuid bit set (see chmod).

• While mktree (p) creates RCS symbolic links in the programmer directory hierarchy, these are not used by ao. Their main function is to allow gmake (p) to check out the makefile for a directory automatically. They also allow RCS utilities such as alog (p) and rlog to be applied readily to the slave RCS repository. ao does not make use of these RCS symbolic links but deals directly with the AIPS++ master repository by specifying absolute pathnames.

• Checkouts may be disabled by creating a file $MSTRETCD/ai_disable. If this file contains any text it will be printed as an informative message.

Diagnostics

Status return values
0: success
1: initialization error, no checkout
2: checkout failure

Examples

The command

   ao -l Foo.cc

would check out Foo.cc with an exclusive lock. Then

   ao -u Foo.cc

would remove the lock without checking the file in or deleting the working copy. The command

   ao -l RCS/*,v

would check out everything in the directory (that is, assuming that RCS is a symlink into the slave directory, all files currently in the slave directory will be checked out of the master).

Bugs

• If the network fails part-way through a checkout, or if the checkout is aborted before completion, an RCS semaphore file with a name of the form ,*, may be left behind in the master RCS repository. The presence of this empty file will cause subsequent checkins or checkouts to report an ``in use'' error. If the not deleted manually by using the ae (p) command, or ai -ae, the semaphore file will eventually be cleaned out by exhale (p) which deletes all such files which are more than one day old.

• Since ao operates over the internet the file transfers are subject to network corruption. On a several occasions, usually when the network response was unusually poor, truncation of the last few characters of a file has been observed. A utility, xrcs (p), is available to verify the internal consistency of RCS version files.

• ao invokes RCS commands directly on the master RCS repository, which may be NFS mounted from a machine on the other side of a slow internet link. A checkout involves reading the RCS version file from the master, inserting the locker's name, then writing it back. These file transfers are handled more efficiently by rao (p).

• ao requires that the host operating system support setuid shell scripts. Some operating systems, most notably Linux and Digital UNIX, do not support setuid shell scripts for security reasons.

See also

The manual page for co(1), the RCS checkout command.
The unix manual page for chmod(1).
AIPS++ variable names (§1.2).
ae (p), AIPS++ RCS semaphore file deletion utility.
ai (p), AIPS++ code checkin utility.
alog (p), AIPS++ change log reporting utility.
amv (p), AIPS++ code rename utility.
au (p), AIPS++ code update utility.
ax (p), AIPS++ code deletion utility.
mktree (p), create AIPS++ directory hierarchy.
rao (p), invoke ao remotely via ssh(1).

Author

Original: 1992/04/28 by Mark Calabretta, ATNF.