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- EXPR ST-UNIX User's Manual EXPR
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- COMMAND
- expr - evaluate arguments as an expression
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- FORMAT
- expr arg...
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- DESCRIPTION
- The arguments which must be separated by whitwe space are
- taken as an expression to be evaluated. The result is writ-
- ten on the standard output. The operators are listed below
- in order of increasing precedence, parentheses may be used
- for grouping but must be separate tokens.
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- _✓e_✓x_✓p_✓r | _✓e_✓x_✓p_✓r
- yields the first _✓e_✓x_✓p_✓r if it is neither null nor `0',
- otherwise yields the second _✓e_✓x_✓p_✓r.
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- _✓e_✓x_✓p_✓r & _✓e_✓x_✓p_✓r
- yields the first _✓e_✓x_✓p_✓r if neither _✓e_✓x_✓p_✓r is null or `0',
- otherwise yields `0'.
-
- _✓e_✓x_✓p_✓r _✓r_✓e_✓l_✓o_✓p _✓e_✓x_✓p_✓r
- where _✓r_✓e_✓l_✓o_✓p is one of < <= = != >= >, yields `1' if the
- comparison is true, `0' if false. If both _✓e_✓x_✓p_✓r are
- integers then the comparison is numeric, otherwise it
- is alphabetic.
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- _✓e_✓x_✓p_✓r + _✓e_✓x_✓p_✓r
- _✓e_✓x_✓p_✓r - _✓e_✓x_✓p_✓r
- addition or subtraction of the arguments.
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- _✓e_✓x_✓p_✓r * _✓e_✓x_✓p_✓r
- _✓e_✓x_✓p_✓r / _✓e_✓x_✓p_✓r
- _✓e_✓x_✓p_✓r % _✓e_✓x_✓p_✓r
- multiplication, division, or remainder of the argu-
- ments.
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- ( _✓e_✓x_✓p_✓r )
- parentheses for grouping.
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- Examples:
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- To add 5 to the Shell variable _✓b:
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- b=`expr $b + 5`
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- _✓e_✓x_✓p_✓r returns 0 if the neither expression is null or '0', 1
- if the either expression is null or '0', 2 for invalid argu-
- ments.
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- Printed 28/March/1988 30 March 1987 1
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