Open System Services Management and Operations Guide (G06.27+, H06.04+)

Managing OSS Files
Open System Services Management and Operations Guide—527191-003
6-27
Redirecting OSS Standard Files
Verifying a Restored OSS File Backup
The dircmp utility reads two directories, compares their contents, and writes the
results to the standard output file. Use dircmp to determine whether the contents of
two directories differ in any way, such as when you restore backed-up files to a new
location and want to be sure the contents are copied correctly.
The dircmp utility compares the filenames in each directory. When the same filename
appears in both, dircmp compares the contents of the two files. In the output, dircmp
first lists the files unique to each directory, then lists the files that have identical names
but different contents. By default, dircmp also lists files that have both identical names
and identical contents.
For more information about the dircmp command, see the dircmp(1) reference
page either online or in the Open System Services Shell and Utilities Reference
Manual.
Redirecting OSS Standard Files
OSS processes use a different set of default files and a different file format than
Guardian processes do. An OSS process always has three unstructured standard files,
usually referred to in UNIX documentation as stdin, stdout, and stderr.
In a UNIX environment, these three files are usually associated with the user’s
terminal: standard input is read from the terminal keyboard, standard output is sent to
the terminal display, and standard error is an output logging mechanism that is usually
also written to the terminal display. Data read or written through these files can be
redirected using shell redirection specifications to other processes or to regular (disk)
files. On a UNIX system, the pseudo-TTY feature ptty can be used as a source or
sink for such data redirection; although the OSS environment does not have a pseudo-
TTY feature, OSSTTY can do similar data redirection.
A Guardian process has three standard files, comparable to the OSS files mentioned
above, that normally possess the structure of an EDIT file:
•
STDIN, usually called the IN file in commands entered from a TACL prompt
•
STDOUT, usually called the OUT file in commands entered from a TACL prompt
•
STDERR, usually called the TERM file in commands entered from a TACL prompt
By default, these files are associated with the user’s home terminal (HOMETERM).
However, the command that runs a Guardian process can redirect those files to
Guardian processes or files.
An OSS user normally launches an OSS shell by logging in through Telserv, most
commonly by starting a TACL session and entering the OSH command. That access
method leaves the OSS standard files associated with the user’s terminal but allows no
way for those files to be redirected to Guardian processes or files.
The OSSTTY utility, described in OSSTTY on page C-1, removes that restriction. To an
OSS process, OSSTTY appears to be a set of three terminal devices (one for each