Commit | Line | Data |
---|---|---|

984263bc MD |
1 | .\" -*- nroff -*- |

2 | .\" | |

3 | .\" Copyright (c) 1993 Winning Strategies, Inc. | |

4 | .\" All rights reserved. | |

5 | .\" | |

6 | .\" Redistribution and use in source and binary forms, with or without | |

7 | .\" modification, are permitted provided that the following conditions | |

8 | .\" are met: | |

9 | .\" 1. Redistributions of source code must retain the above copyright | |

10 | .\" notice, this list of conditions and the following disclaimer. | |

11 | .\" 2. Redistributions in binary form must reproduce the above copyright | |

12 | .\" notice, this list of conditions and the following disclaimer in the | |

13 | .\" documentation and/or other materials provided with the distribution. | |

14 | .\" 3. All advertising materials mentioning features or use of this software | |

15 | .\" must display the following acknowledgement: | |

16 | .\" This product includes software developed by Winning Strategies, Inc. | |

17 | .\" 4. The name of the author may not be used to endorse or promote products | |

18 | .\" derived from this software without specific prior written permission | |

19 | .\" | |

20 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |

21 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |

22 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |

23 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |

24 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |

25 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |

26 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |

27 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |

28 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |

29 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |

30 | .\" | |

31 | .\" $FreeBSD: src/bin/expr/expr.1,v 1.9.2.4 2003/05/16 22:55:19 keramida Exp $ | |

32 | .\" | |

97861a1d | 33 | .Dd April 10, 2013 |

984263bc MD |
34 | .Dt EXPR 1 |

35 | .Os | |

36 | .Sh NAME | |

37 | .Nm expr | |

38 | .Nd evaluate expression | |

39 | .Sh SYNOPSIS | |

40 | .Nm | |

41 | .Ar expression | |

42 | .Sh DESCRIPTION | |

43 | The | |

44 | .Nm | |

45 | utility evaluates | |

46 | .Ar expression | |

47 | and writes the result on standard output. | |

48 | .Pp | |

49 | All operators and operands must be passed as separate arguments. | |

50 | Several of the operators have special meaning to command interpreters | |

51 | and must therefore be quoted appropriately. | |

52 | All integer operands are interpreted in base 10. | |

53 | .Pp | |

54 | Arithmetic operations are performed using signed integer math. | |

55 | .Pp | |

56 | Operators are listed below in order of increasing precedence; all | |

57 | are left-associative. | |

58 | Operators with equal precedence are grouped within { } symbols. | |

59 | .Bl -tag -width indent | |

cd27fdd2 | 60 | .It Ar expr1 | expr2 |

984263bc MD |
61 | Return the evaluation of |

62 | .Ar expr1 | |

63 | if it is neither an empty string nor zero; | |

64 | otherwise, returns the evaluation of | |

65 | .Ar expr2 . | |

66 | .It Ar expr1 Li & Ar expr2 | |

67 | Return the evaluation of | |

68 | .Ar expr1 | |

69 | if neither expression evaluates to an empty string or zero; | |

70 | otherwise, returns zero. | |

71 | .It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2 | |

72 | Return the results of integer comparison if both arguments are integers; | |

73 | otherwise, returns the results of string comparison using the locale-specific | |

74 | collation sequence. | |

75 | The result of each comparison is 1 if the specified relation is true, | |

76 | or 0 if the relation is false. | |

77 | .It Ar expr1 Li "{+, -}" Ar expr2 | |

78 | Return the results of addition or subtraction of integer-valued arguments. | |

79 | .It Ar expr1 Li "{*, /, %}" Ar expr2 | |

80 | Return the results of multiplication, integer division, or remainder of integer-valued arguments. | |

81 | .It Ar expr1 Li : Ar expr2 | |

82 | The | |

83 | .Dq \&: | |

84 | operator matches | |

85 | .Ar expr1 | |

86 | against | |

87 | .Ar expr2 , | |

88 | which must be a regular expression. The regular expression is anchored | |

89 | to the beginning of the string with an implicit | |

90 | .Dq ^ . | |

91 | .Pp | |

92 | If the match succeeds and the pattern contains at least one regular | |

93 | expression subexpression | |

94 | .Dq "\e(...\e)" , | |

95 | the string corresponding to | |

96 | .Dq "\e1" | |

97 | is returned; | |

98 | otherwise the matching operator returns the number of characters matched. | |

99 | If the match fails and the pattern contains a regular expression subexpression | |

100 | the null string is returned; | |

101 | otherwise 0. | |

102 | .El | |

103 | .Pp | |

104 | Parentheses are used for grouping in the usual manner. | |

97861a1d SW |
105 | .Sh EXIT STATUS |

106 | The | |

107 | .Nm | |

108 | utility exits with one of the following values: | |

109 | .Bl -tag -width indent -compact | |

110 | .It 0 | |

111 | the expression is neither an empty string nor 0. | |

112 | .It 1 | |

113 | the expression is an empty string or 0. | |

114 | .It 2 | |

115 | the expression is invalid. | |

116 | .El | |

984263bc MD |
117 | .Sh EXAMPLES |

118 | .Bl -enum | |

119 | .It | |

120 | The following example adds one to the variable a. | |

121 | .Dl a=`expr $a + 1` | |

122 | .It | |

123 | The following example returns the filename portion of a pathname stored | |

124 | in variable a. The // characters act to eliminate ambiguity with the | |

125 | division operator. | |

126 | .Dl expr "//$a" Li : '.*/\e(.*\e)' | |

127 | .It | |

128 | The following example returns the number of characters in variable a. | |

129 | .Dl expr $a Li : '.*' | |

130 | .El | |

984263bc MD |
131 | .Sh SEE ALSO |

132 | .Xr sh 1 , | |

133 | .Xr test 1 | |

134 | .Sh STANDARDS | |

135 | The | |

136 | .Nm | |

137 | utility conforms to | |

138 | .St -p1003.2 . |