Shell Programming/expr command
expr 1 | expr 2
[edit | edit source]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
[edit | edit source]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
[edit | edit source]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.