expr

Overview ¶

Package expr implements the `expr` built-in.

expr evaluates a single expression made of operators and operands. Operator precedence (lowest → highest):

|                logical or
&                logical and
= != < > <= >=   comparison
+ -              addition / subtraction
* / %            multiplication / division / modulo
: STRING         regex anchor-match (BRE), returns matched substring or length
( EXPR )         grouping

String comparisons fall through to numeric when both sides parse as integers. expr exits with:

0 if the result is non-zero AND non-empty
1 if the result is 0 or empty
2 on syntax error (and writes "expr: ..." to stderr)