Name
expr expression
— coreutils
Synopsis
/usr/bin
stdin stdout - file -- opt --help --version
The expr
command does simple math (and other expression evaluation) on the command line:
$ expr 7 + 3
10
$ expr '(' 7 + 3 ')' '*' 14 Special shell characters are quoted
140
$ expr length ABCDEFG
7
$ expr 15 '>' 16
0
Each argument must be separated by whitespace. Notice we had to quote or escape any characters that have special meaning to the shell. Parentheses (escaped) may be used for grouping. Table 1-10 lists operators for expr
.
Operator | Numeric operation | String operation |
| Addition | |
| Subtraction | |
| Multiplication | |
| Integer division | |
| Remainder (modulo) | |
| Less than | Earlier in dictionary |
| Less than or equal | Earlier in dictionary, or equal |
| Greater than | Later in dictionary |
| Greater than or equal | Later in dictionary, or equal |
| Equality | Equality |
| Inequality | Inequality |
| Boolean “or” | Boolean “or” |
| Boolean “and” | Boolean “and” |
| Does the regular expression | |
| Print | |
| Return the index of the first position in string |
For Boolean expressions, the number 0 and the empty string are considered false; any other value is true. For Boolean results, 0 is false and 1 is true.
expr
is not very efficient. For more complex needs, consider using a language like Perl instead. ...
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