expr(1) 						      General Commands Manual							   expr(1)

NAME

       expr - Evaluates arguments as expressions

SYNOPSIS

       expr expression

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       expr:  XCU5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

OPTIONS

       None

OPERANDS

       The  single expression evaluated by expr will be formed from the operands, as described in the DESCRIPTION section.  Each of the expression
       operator symbols: (   )	 |   &	 = > >=   <   <=   !=	+   -	*   /	%   : and the symbols integer and string in the  DESCRIPTION  sec-
       tion must be provided as separate arguments to expr.  Expression to be evaluated, formed as explained in the DESCRIPTION section.

DESCRIPTION

       The  expr  command  reads  an expression, evaluates it, and writes the result to standard output.  Within the expression argument, you must
       separate each term with spaces, precede characters special to the shell with a  (backslash), and quote strings containing spaces or  other
       special	characters.   Note that expr returns 0 to indicate a zero value, rather than the null string.  Integers can be preceded by a unary
       minus sign.  Internally, integers are treated as 64-bit or 32-bit two's complement numbers, depending on the  word  size  of  the  hardware
       platform.

       The  operators  and  keywords  are described in the following listing.  Characters that need to be escaped are preceded by a  (backslash).
       The list is in order of increasing precedence with equal precedence operators grouped within {} (braces).  Returns  expression1	if  it	is
       neither	null nor 0 (zero); otherwise, returns expression2.  Returns expression1 if neither expression1 nor expression2 is null nor 0; oth-
       erwise, returns 0.  Returns the result of an integer comparison if both expressions are integers; otherwise, returns the result of a string
       comparison.   Adds or subtracts integer-valued arguments.  Multiplies, divides, or provides the remainder from the division of integer-val-
       ued arguments.  Compares expression1 with expression2, which must be a basic regular expression, with syntax as described for grep,  except
       that  all  patterns are anchored, so ^ (circumflex) (which anchors a pattern to the beginning of a line) is not a special character in this
       context.

	      Normally, the matching operator returns the number of characters matched.  Alternatively, you can use the (...) symbols in expres-
	      sion2  to  return a portion of expression1.  Provides expression grouping.  An argument consisting only of an (optional) unary minus
	      followed by digits.  A string argument.  Refer to the STRING OPERAND section.

       To avoid unpredictable results when using a range expression to match a class of characters, use a character class expression rather than a
       standard range expression.  For information about character class expressions, see the discussion of this topic included in the description
       of the grep command.

   FUNCTIONS
       [Tru64 UNIX]  The expr command provides the following string-expression functions.  Strings containing  white  space  must  be  quoted.	 A
       string  argument  should  not  be  one of the expression operator symbols shown in the OPERANDS section or one of the string function names
       below. You cannot use, for example, match "$subject" "$pattern" unless it is confirmed that subject and pattern do not  match  this  viola-
       tion.  The  first  character of a string is position 1.	The information returned by all these functions is in the form of a string: [Tru64
       UNIX]  Compares each character in the second string against each character in the first string and returns the position in the first string
       of  the first match found, where the first match is the match closest to the beginning of string1.  [Tru64 UNIX]  Returns the length of the
       string argument.  [Tru64 UNIX]  See the description of the : (colon) match operator, above.  [Tru64 UNIX]  Returns the substring of  string
       that begins at character position start and is length characters long.

   STRING OPERAND
       A string argument is an argument that cannot be identified as an integer argument or as one of the expression operator symbols shown in the
       OPERANDS section.

       The use of string arguments length, substr, index or match produces unspecified results.

EXIT STATUS

       The expr command returns the following exit values: The expression is neither null nor 0.  The expression is null or 0.	The expression	is
       invalid.  An error occurred.

EXAMPLES

       To increment a shell variable, enter: COUNT=`expr $COUNT + 1`

	      This  adds  1  to  the COUNT shell variable (see sh for details).  To find the length of a shell variable, enter: RES=`expr "$VAR" :
	      ".*"`

	      Note that VAR is in double quotes to avoid problems where VAR is NULL or contains embedded spaces.  The regular expression  is  also
	      quoted  to  avoid  expansion  by the shell. This operation can also be performed as: RES=`expr length "$VAR"` To use part of a shell
	      variable, enter: RES=`expr "$VAR" : "-*(.*)"`

	      This removes leading - (dashes), if any, from VAR. If the ( ) characters were omitted, RES would contain the length  of  VAR.	To
	      find a character from one string in another string, enter: INDEX=`expr index "Hello World!" "Wo"`

	      Note  that the returned value is 5, not 7.  The first match is the fifth character in string1, matching the o in string2 rather than
	      the W, which is the seventh character in string1.  Special considerations: RES=`expr "x$VAR" : "x-*(.*)"`

	      This succeeds even if VAR has the value - (dash).  RES=`expr "x$VAR" = "x="

	      This succeeds even if VAR has the value = (equal sign).

ENVIRONMENT VARIABLES

       The following environment variables affect the execution of expr: Provides a default value for the internationalization variables that  are
       unset  or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari-
       ables contain an invalid setting, the utility behaves as if none of the variables had been defined.  If set to a  non-empty  string  value,
       overrides  the  values of all the other internationalization variables.	Determines the locale for the interpretation of sequences of bytes
       of text data as characters (for example, single-byte as opposed to multibyte characters in arguments) and the behavior of character classes
       in  regular  expressions..  Determines the locale for the format and contents of diagnostic messages written to standard error.	Determines
       the location of message catalogues for the processing of LC_MESSAGES.

SEE ALSO

       Commands:  grep(1), Bourne shell sh(1b), POSIX shell sh(1p), test(1)

       Functions:  string(3), wcscat(3)

       Standards:  standards(5)

																	   expr(1)