typeset

Declare an integer variable

$ typeset -i [count]=0

$ typeset -r [CONSTANT]="[value]"

$ typeset -u [name]="[value]"

$ typeset -l [name]="[VALUE]"

$ typeset -x [PATH]="[/usr/bin]"

$ typeset -a [myarray]=([one] [two] [three])

$ typeset -A [mymap]=([key1]="[val1]" [key2]="[val2]")

$ typeset -i

typeset [-aAfFgilnrtux] [-p] [name[=value]...]

typeset is a shell builtin that declares variables and assigns them attributes. In bash, it is a synonym for declare and is provided for compatibility with ksh (KornShell).
Variables can be given type attributes like integer (-i) for automatic arithmetic evaluation, or transformation attributes like uppercase (-u) and lowercase (-l). The read-only attribute (-r) prevents modification after assignment.
When used inside a function without -g, typeset creates a local variable that shadows any global variable of the same name. The variable is restored when the function exits.
Without arguments, typeset displays all variables with their attributes. With attribute flags alone (e.g., typeset -i), it lists variables having that attribute.

-a

Declare indexed array variable

Declare associative array variable (bash 4+)

Display function names and definitions

Display function names only

Create global variable when used in a function (bash only)

Treat variable as integer; arithmetic evaluation on assignment

Convert value to lowercase on assignment

Create nameref (reference to another variable)

Make variable read-only

Give variable the trace attribute

Convert value to uppercase on assignment

Export variable to environment of child processes

Display attributes and values of variables

In bash, typeset is marked as obsolete in favor of declare, but both work identically. Behavior differs between shells (bash, ksh, zsh). The -n nameref option requires bash 4.3+ or ksh93. Associative arrays (-A) require bash 4+.

typeset originated in the KornShell (ksh) developed by David Korn at Bell Labs in the early 1980s. When bash was created, it implemented similar functionality as declare but included typeset as an alias for ksh compatibility. The command remains important for portable shell scripts targeting multiple Korn-like shells.

declare(1), local(1), export(1), readonly(1), bash(1)