⊕ Usage

export name[=word] ...
export -p
readonly name[=word] ...
readonly -p

⊕ Purpose

 

export modifies or prints the environment. readonly makes variables unmodifiable.

⊕ Major options

 

-p

 

Print the name of the command and the names and values of all exported (read-only) variables in such a way as to allow the shell to reread the output to re-create the environment (read-only settings).

⊕ Behavior

 

With the -p option, both commands print their name and all variables and values that are exported or read-only, respectively. Otherwise, they apply the appropriate attribute to the named variables.

⊕ Caveats

 

The versions of /bin/sh on many commercial Unix systems are (sadly) still not POSIX-compliant. Thus the variable-assignment form of export and readonly don't work. For strictest portability, use:

FOO=somevalue
export FOO

BAR=anothervalue
readonly BAR