vc(1)
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vc Command
version control
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SYNTAX
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. User-declared
keywords 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 statements) of
keyword values specified in control statements or as vc command
arguments.
A control statement is a single line beginning with a control
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 character 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 fewer 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. You can include an
uninterpreted control character 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 surrounded by
control characters with their assigned value
in all text lines, not just in vc statements.
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-t All characters from the beginning of a line
up to and including the first tab character
are ignored for the purpose of 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 diagnostic
output.
Version Control Statements
:dcl keyword[, ..., keyword]
Declares keywords. All keywords must be declared.
:asg keyword=value
Assigns 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
Skips lines of the standard input. If the condition is true
all lines between the if statement and the matching end
statement are copied to the standard output. If the
condition is false, all intervening lines are discarded,
including control statements. Note that intervening if
statements and matching end statements are recognized only
for 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
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| Or
> Greater than
< Less than
( ) Used for logical groupings
not May occur only 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
&
|
Use parentheses to alter the order of precedence.
Separate values from operators or parentheses by at least
one blank or tab.
::text
Replaces keywords on lines that are copied to the standard
output. The two leading control characters 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
Turns on or off keyword replacement on all lines.
:ctl char
Changes 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).
DIAGNOSTICS
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vc(1)
Use help(1) for explanations.
EXIT CODES
0--Normal
1--Any error
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