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Annotation of 43BSDReno/bin/expr/expr.1, revision 1.1.1.1

1.1       root        1: .\"    @(#)expr.1      6.1 (Berkeley) 4/29/85
                      2: .\"
                      3: .TH EXPR 1 "April 29, 1985"
                      4: .AT 3
                      5: .SH NAME
                      6: expr \- evaluate arguments as an expression
                      7: .SH SYNOPSIS
                      8: .B expr
                      9: arg
                     10: .B .\|.\|.
                     11: .SH DESCRIPTION
                     12: The arguments are taken as an expression.
                     13: After evaluation, the result is written on the standard output.
                     14: Each token of the expression is a separate argument.
                     15: .PP
                     16: The operators and keywords are listed below.
                     17: The list is in order of increasing precedence,
                     18: with equal precedence operators grouped.
                     19: .TP
                     20: .I expr | expr
                     21: yields the first
                     22: .I expr
                     23: if it is neither null nor `0', otherwise
                     24: yields the second
                     25: .I expr.
                     26: .TP
                     27: .I expr & expr
                     28: yields the first
                     29: .I expr
                     30: if neither
                     31: .I expr
                     32: is null or `0', otherwise yields `0'.
                     33: .TP
                     34: .I expr relop expr
                     35: where
                     36: .I relop is one of
                     37: < <= = != >= >,
                     38: yields `1' if the indicated comparison is true, `0' if false.
                     39: The comparison is numeric if both
                     40: .I expr
                     41: are integers, otherwise lexicographic.
                     42: .TP
                     43: .IR expr " + " expr
                     44: .br
                     45: .ns
                     46: .TP
                     47: .IR expr " \- " expr
                     48: .br
                     49: addition or subtraction of the arguments.
                     50: .TP
                     51: .IR expr " * " expr
                     52: .br
                     53: .ns
                     54: .TP
                     55: .IR expr " / " expr
                     56: .br
                     57: .ns
                     58: .TP
                     59: .IR expr " % " expr
                     60: .br
                     61: multiplication, division, or remainder of the arguments.
                     62: .TP
                     63: .IR expr " : " expr
                     64: The matching operator compares the string first argument
                     65: with the regular expression second argument;
                     66: regular expression syntax is the same as that of
                     67: .IR ed (1).
                     68: The
                     69: \fB\\(\|.\|.\|.\|\\)\fP
                     70: pattern symbols can be used to select a portion of the
                     71: first argument.
                     72: Otherwise,
                     73: the matching operator yields the number of characters matched
                     74: (`0' on failure).
                     75: .TP
                     76: .RI ( " expr " )
                     77: parentheses for grouping.
                     78: .PP
                     79: Examples:
                     80: .PP
                     81: To add 1 to the Shell variable
                     82: .IR a :
                     83: .IP
                     84: a=\`expr $a + 1\`
                     85: .PP
                     86: To find the filename part (least significant part)
                     87: of the pathname stored in variable
                     88: .I a,
                     89: which may or may not contain `/':
                     90: .IP
                     91: expr $a : \'.*/\e(\^.*\e)\' \'\^|\' $a
                     92: .LP
                     93: Note the quoted Shell metacharacters.
                     94: .SH "SEE ALSO"
                     95: sh(1), test(1)
                     96: .SH DIAGNOSTICS
                     97: .I Expr
                     98: returns the following exit codes:
                     99: .PP
                    100:        0       if the expression is neither null nor `0',
                    101: .br
                    102:        1       if the expression
                    103: is null or `0',
                    104: .br
                    105:        2       for invalid expressions.

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