vc(1)							      General Commands Manual							     vc(1)

NAME

       vc - substitutes assigned values in place of identification keywords.

SYNOPSIS

       char] [keyword=value ... keyword=value]

DESCRIPTION

       The or version control command copies lines from the standard input to the standard output under control of command line arguments and con-
       trol statements encountered in the standard input.  In the process of performing the copy operation, user declared keywords can 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 stan-
       dard output is conditional, based on tests of keyword values specified in control statements or on command arguments.

       Replacement of keywords by values is done whenever a keyword surrounded by control characters is encountered on a  version  control  state-
       ment.   The  option  forces replacement of keywords in all lines of text.  An uninterpreted control character can be included in a value by
       preceding it with If a literal is desired, it too must be preceded by

       The command is part of the SCCS (Source Code Control System) command suite.

   Options
       recognizes the following options and arguments:

	      Replace keywords surrounded by control characters
			with their assigned value in all text lines and not just in statements.

	      Ignore all characters from the beginning of a line
			up to and including the first tab character for the purpose of detecting a control statement.  If one is found, all  char-
			acters up to and including the tab are discarded.

	      Specify a control character to be used in place of

	      Silence warning messages (not errors) that are normally printed
			on the diagnostic output.

   Control Statements
       A control statement is a single line beginning with a control character, and the default control character is colon (Unless the and options
       are used [See above]).  Input lines beginning with a backslash followed by the 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 alphanumeric characters of which the first character is alphabetic.	A value is any ASCII  string  that
       can be created using (see ed(1)); a numeric value is an unsigned string of digits.  Keyword values must not contain spaces or tabs.

       Version control statements occur in the following forms:

	      :dcl keyword[, ..., keyword]
				Used to declare keywords.  All keywords must be declared.

	      :asg keyword=value
				Used  to  assign  values  to keywords.	An statement overrides the assignment for the corresponding keyword on the
				command line and all previous for that keyword.  Keywords declared, but not assigned values have null values.

	      Used to skip 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 solely for the purpose of maintain-
				ing the proper if-end matching.

				The syntax of a condition may include the following:

				     <cond>    ::= [ "not" ] <or>
				     <or>      ::= <and> | <and> "|" <or>
				     <and>     ::= <exp> | <exp> "&" <and>
				     <exp>     ::= "(" <or> ")" | <value> <op> <value>
				     <op>      ::= "=" | "!=" | "<" | ">"
				     <value>   ::= <arbitrary ASCII string> | <numeric string>

				The following are available operators and their meanings:

				     equal
				     not equal
				     and
				     or
				     greater than
				     less than
				     used for logical groupings
				     allowed only immediately after the
					       if, and when present, inverts the value of the entire condition

				The and operate only on unsigned integer values (such as is false).  All other operators take strings as arguments
				(for example, is true).  The precedence of the operators (from highest to lowest) is as follows:

				     all of equal precedence

					      Parentheses can be used to alter the order of precedence.
				Values must be separated from operators or parentheses by at least one space or tab.

	      Used for keyword replacement 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 option.

	      Turn on or off keyword replacement on all lines.

	      Change the control character to char.

	      Prints the given message on the diagnostic output.

	      Prints the given message followed by:

				on the diagnostic output.  halts execution and returns an exit code of 1.

EXTERNAL INFLUENCES

   Environment Variables
       determines the interpretation of keywords, values, the control character assigned through and within  text  as  single-	and/or	multi-byte
       characters.

       determines the language in which messages are displayed.

       If is not specified in the environment or is set to the empty string, the value of is used as a default for each unspecified or empty vari-
       able.  If is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead  of  If  any  internationalization
       variable contains an invalid setting, behaves as if all internationalization variables are set to "C".  See environ(5).

RETURN VALUE

       returns 0 on normal completion; 1 if an error occurs.

DIAGNOSTICS

       Use sccshelp(1) for explanations.

SEE ALSO

       ed(1), sccshelp(1).

																	     vc(1)