VC(1-SysV) RISC/os Reference Manual VC(1-SysV)
NAME
vc - version control
SYNOPSIS
vc [-a] [-t] [-cchar] [-s] [keyword=value ... keyword=value]
DESCRIPTION
The vc command copies lines from the standard input to the
standard output under control of its arguments and control
statements encountered in the standard input. In the pro-
cess of performing the copy operation, user declared key-
words may be replaced by their string value when they appear
in plain text and/or control statements.
The copying of lines from the standard input to the standard
output is conditional, based on tests (in control state-
ments) of keyword values specified in control statements or
as vc command arguments.
A control statement is a single line beginning with a con-
trol character, except as modified by the -t keyletter (see
below). The default control character is colon (:), except
as modified by the -c keyletter (see below). Input lines
beginning with a backslash (\) followed by a control charac-
ter are not control lines and are copied to the standard
output with the backslash removed. Lines beginning with a
backslash followed by a non-control character are copied in
their entirety.
A keyword is composed of 9 or less alphanumerics; the first
must be alphabetic. A value is any ASCII string that can be
created with ed(1); a numeric value is an unsigned string of
digits. Keyword values may not contain blanks or tabs.
Replacement of keywords by values is done whenever a keyword
surrounded by control characters is encountered on a version
control statement. The -a keyletter (see below) forces
replacement of keywords in all lines of text. An uninter-
preted control character may be included in a value by
preceding it with \. If a literal \ is desired, then it too
must be preceded by \.
Keyletter Arguments
-a Forces replacement of keywords sur-
rounded by control characters with their
assigned value in all text lines and not
just in vc statements.
-t All characters from the beginning of a
line up to and including the first tab
character are ignored for the purpose of
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detecting a control statement. If one
is found, all characters up to and
including the tab are discarded.
-cchar Specifies a control character to be used
in place of :.
-s Silences warning messages (not error)
that are normally printed on the diag-
nostic output.
Version Control Statements
:dcl keyword[, ..., keyword]
Used to declare keywords. All keywords
must be declared.
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:asg keyword=value
Used to assign values to keywords. An
asg statement overrides the assignment
for the corresponding keyword on the vc
command line and all previous asg's for
that keyword. Keywords declared, but
not assigned values have null values.
:if condition
.
.
:end
Used to skip lines of the standard input. If the condi-
tion is true all lines between the if statement and the
matching end statement are copied to the standard out-
put. If the condition is false, all intervening lines
are discarded, including control statements. Note that
intervening if statements and matching end statements
are recognized solely for the purpose of maintaining
the proper if-end matching.
The syntax of a condition is:
<cond> ::= [ "not" ] <or>
<or> ::= <and> | <and> "|" <or>
<and> ::= <exp> | <exp> "&" <and>
<exp> ::= "(" <or> ")" | <value> <op> <value>
<op> ::= "=" | "!=" | "<" | ">"
<value> ::= <arbitrary ASCII string> | <numeric string>
The available operators and their meanings are:
= equal
!= not equal
& and
| or
> greater than
< less than
( ) used for logical groupings
not may only occur immediately after the if, and
when present, inverts the value of the
entire condition
The > and < operate only on unsigned integer values
(e.g., : 012 > 12 is false). All other operators take
strings as arguments (e.g., : 012 != 12 is true). The
precedence of the operators (from highest to lowest)
is:
= != > < all of equal precedence
&
|
Parentheses may be used to alter the order of pre-
cedence.
Values must be separated from operators or parentheses
by at least one blank or tab.
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::text
Used for keyword replacement on lines that are copied
to the standard output. The two leading control char-
acters are removed, and keywords surrounded by control
characters in text are replaced by their value before
the line is copied to the output file. This action is
independent of the -a keyletter.
:on
:off
Turn on or off keyword replacement on all lines.
:ctl char
Change the control character to char.
:msg message
Prints the given message on the diagnostic output.
:err message
Prints the given message followed by:
ERROR: err statement on line ... (915)
on the diagnostic output. vc halts execution, and
returns an exit code of 1.
SEE ALSO
ed(1), help(1) in the User's Reference Manual.
DIAGNOSTICS
Use help(1) for explanations.
EXIT CODES
0 - normal
1 - any error
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