The operators and keywords are listed below.
The list is in order of increasing precedence,
with equal precedence operators grouped.
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expr | expr |
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yields the first
expr if it is neither null nor '0', otherwise
yields the second
expr. |
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expr & expr |
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yields the first
expr if neither
expr is null or '0', otherwise yields '0'.
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expr relop expr |
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where
relop is one of < <= = != >= >,
yields '1' if the indicated comparison is true, '0' if false.
The comparison is numeric if both
expr are integers, otherwise lexicographic.
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expr + expr |
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expr - expr
addition or subtraction of the arguments.
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expr * expr |
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expr / expr
expr % expr
multiplication, division, or remainder of the arguments.
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expr : expr |
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The matching operator compares the string first argument
with the regular expression second argument.
Regular expression syntax is the same as that of
ed(1);
/usr/5bin/expr uses simple regular expressions,
/usr/5bin/posix/expr, /usr/5bin/posix2001/expr, and
/usr/5bin/s42/expr use basic regular expressions.
The
\(...\)
pattern symbols can be used to select a portion of the
first argument.
Otherwise,
the matching operator yields the number of characters matched
('0' on failure).
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match expr expr |
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Same as
expr : expr. |
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( expr ) |
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parentheses for grouping.
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string |
Yields itself
unless it is part of a larger expression.
With
/usr/5bin/posix/expr and
/usr/5bin/posix2001/expr, all
strings that form valid decimal numbers
are converted to the canonical form.
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The following operators are supported only by
/usr/5bin/s42/expr or if the
SYSV3 environment variable is set:
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length string |
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Returns the number of characters in
string. |
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substr string index count |
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Returns a string that consists of
count characters
beginning at position
index of
string (starting at 1).
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index string set |
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Returns the index in
string (starting at 1) of the first occurrence
of one of the characters in
set, or 0 if no character is found.
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