expr

Evaluate expressions and manipulate strings. More information: https://www.gnu.org/software/coreutils/manual/html_node/expr-invocation.html.

• Get the length of a specific string:

expr length "{{string}}"

• Get the substring of a string with a specific length:

expr substr "{{string}}" {{from}} {{length}}

• Match a specific substring against an anchored pattern:

expr match "{{string}}" '{{pattern}}'

• Get the first char position from a specific set in a string:

expr index "{{string}}" "{{chars}}"

• Calculate a specific mathematic expression:

expr {{expression1}} {{+|-|*|/|%}} {{expression2}}

• Get the first expression if its value is non-zero and not null otherwise get the second one:

expr {{expression1}} \| {{expression2}}

• Get the first expression if both expressions are non-zero and not null otherwise get zero:

expr {{expression1}} \& {{expression2}}