Export built-in
The export built-in exports variables to the environment.
Synopsis
export [-p] [name[=value]…]
Description
The export built-in (without the -p option) exports variables of the specified names to the environment, with optional values. If no names are given, or if the -p option is given, the names and values of all exported variables are displayed. If the -p option is given with operands, only the specified variables are displayed.
Options
The -p (--print) option causes the shell to display the names and
values of all exported variables in a format that can be reused as input to
restore the state of these variables. When used with operands, the option
limits the output to the specified variables.
Operands
The operands are the names of variables to be exported or printed. When exporting, each name may optionally be followed by = and a value to assign to the variable.
Standard output
When exporting variables, the export built-in does not produce any output.
When printing variables, the built-in prints simple commands that invoke the export built-in to reexport the variables with the same values. Note that the commands do not include options to restore the attributes of the variables, such as the -r option to make variables read-only.
For array variables, the export built-in invocation is preceded by a separate assignment command since the export built-in does not support assigning values to array variables.
Errors
When exporting a variable with a value, it is an error if the variable is read-only.
When printing variables, it is an error if an operand names a non-existing variable.
Exit status
Zero unless an error occurs.
Examples
Compatibility
This built-in is part of the POSIX standard. Printing variables is portable
only when the -p option is used without operands.
Previous versions of yash supported the non-standard -r and -X options, but these are not yet supported in yash-rs.