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Shell Programming/expr command
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expr 1 | expr 2
Expression 1 if expression 1 is non-zero, otherwise expression 2.
expr 1 | expr 2
1 0 -> Expression 1
1 1 -> Expression 1
0 0 -> Expression 2
0 1 -> Expression 2
expr 1 & expr 2
Zero if either expression is zero, otherwise expression 1.
expr 1 & expr 2
0 0 -> 0
1 0 -> 0
0 1 -> 0
1 1 -> Expression 1
Other operations in expr command
The expr command is useful in simple arithmetic operations using integers only.
expr 1 + 1
output:
2
Similarly,
expr 1 - 1
expr 1 * 1
expr 1 / 1
expr 1 % 1
which have following results, respectively: 0; 1; 1; 0. Note that % is modulus.