# Shell Programming/expr command

### expr 1 | expr 2 edit

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

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

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.