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Annotation of researchv10dc/man/adm/man1/expr.1, revision 1.1.1.1

1.1       root        1: .TH EXPR 1
                      2: .CT 1 shell 
                      3: .SH NAME
                      4: expr \- evaluate arguments as an expression
                      5: .SH SYNOPSIS
                      6: .B expr
                      7: .I arg ...
                      8: .SH DESCRIPTION
                      9: The arguments are taken as an expression.
                     10: After evaluation, the result is written on the standard output.
                     11: Each token of the expression is a separate argument.
                     12: .PP
                     13: The operators and keywords are listed below
                     14: in order of increasing precedence,
                     15: with equal precedence operators grouped.
                     16: .TP \w'\f5(\fI\ expr\ \f5)\ 'u
                     17: .IB expr1 " | " expr2
                     18: Value is the value of
                     19: .I expr1
                     20: if that is neither empty nor 0,
                     21: otherwise the value of 
                     22: .IR expr2.
                     23: .TP
                     24: .IB expr1 " & " expr2
                     25: Value is the value of
                     26: .I expr1
                     27: if neither
                     28: .I expr1
                     29: nor
                     30: .I expr2
                     31: is empty or 0, otherwise 0.
                     32: .TP
                     33: .I expr1 relop expr2
                     34: .I Relop
                     35: is one of
                     36: .L "< <= = != >= >" .
                     37: Value is 1
                     38: if the indicated comparison is true, 0
                     39: if false.
                     40: The comparison is numeric if both
                     41: .I expr
                     42: are integers, otherwise lexicographic.
                     43: .TP
                     44: .IB expr1 " + " expr2
                     45: .br
                     46: .ns
                     47: .TP
                     48: .IB expr1 " - " expr2
                     49: .br
                     50: Value is the sum or difference of the (integer) values of 
                     51: .I expr1
                     52: and
                     53: .I expr2.
                     54: .TP
                     55: .IB expr1 " * " expr2
                     56: .br
                     57: .ns
                     58: .TP
                     59: .IB expr1 " / " expr2
                     60: .br
                     61: .ns
                     62: .TP
                     63: .IB expr1 " % " expr2
                     64: .br
                     65: Value is the product, quotient, or remainder of the (integer)
                     66: values of 
                     67: .I expr1
                     68: and
                     69: .I expr2.
                     70: .TP
                     71: .IB expr " : " regexp
                     72: Match the string value of 
                     73: .I expr
                     74: with the regular expression 
                     75: .IR regexp ;
                     76: regular expression syntax is the same as in
                     77: .IR ed (1),
                     78: but matches are anchored at the left.
                     79: On success a subexpression
                     80: .BR \e(\| ... \|\e) ,
                     81: if present in
                     82: .I regexp,
                     83: picks out a return value from the matched string.
                     84: Otherwise,
                     85: the matching operator yields the number of characters matched
                     86: (0 on failure).
                     87: .TP
                     88: .BI ( " expr " )
                     89: Parentheses for grouping.
                     90: .TP
                     91: .I arg
                     92: Value is the string
                     93: .I arg.
                     94: .PP
                     95: .SH EXAMPLES
                     96: .TP
                     97: .L
                     98: a=`expr $a + 1`
                     99: Add 1 to shell variable
                    100: .IR a .
                    101: .TP
                    102: .L
                    103: expr $a : '.*/\e(.*\e)' '|' $a
                    104: Same as
                    105: .LR "basename $a" .
                    106: .SH "SEE ALSO"
                    107: .IR sh (1), 
                    108: .IR test (1)
                    109: .SH DIAGNOSTICS
                    110: .I Expr
                    111: returns exit code 0 if the expression is neither null nor 0,
                    112: 1 if the expression is null or 0, 2 for invalid expressions.

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