export

export name[=value] ...export -pexport [-fn] name[=value] ...

export marks shell variables so they are placed in the environment of subsequently executed commands. An exported variable becomes an environment variable that every child process inherits; a variable set without export stays private to the current shell.This is how configuration reaches programs you run: PATH tells the shell where to find executables, EDITOR tells tools which editor to open, and application-specific variables like JAVA_HOME are read by the processes that need them. Assignment and export can be combined (export FOO=bar) or split across two statements (FOO=bar then export FOO), which is the more portable form for very old shells.The export attribute belongs to the variable, not to its value: once a name is exported, later assignments to it are exported too, without repeating export. export -n removes that attribute while leaving the variable defined in the current shell, which is not the same as deleting it; use unset for that.With no operands, or with -p, export prints the names and values of all exported variables in a format that can be re-read as shell input.

-p

Print all exported variables in a form that can be reused as shell input.

Remove the export attribute from each name. The variable stays set in the current shell but is no longer passed to children. Not POSIX; a bash, ksh and zsh extension.

Treat each name as a shell function rather than a variable. Bash-specific and rarely portable.

End of options; treat the rest as names, even if they start with a dash.

export only affects the current shell and the processes it starts afterwards. It cannot change the environment of the parent shell or of processes that are already running, which is why a script must be sourced (. script.sh) rather than executed if you want its exports to persist in your session.export -n does not unset the variable. The value remains visible to the current shell and to anything using it directly; only inheritance stops. Use unset name to remove it entirely.Exported functions (export -f) are passed to children through specially encoded environment variables and only work when the child is also bash. This mechanism was the vector for the Shellshock vulnerabilities in 2014, and its encoding changed as part of the fix.Only -p is specified by POSIX. -f and -n are extensions, so scripts targeting /bin/sh should avoid them.

export dates to the Bourne shell in the late 1970s and is standardized by POSIX. It is implemented as a shell builtin in every major shell, because an external program could not modify the shell's own environment. Some systems also ship a /usr/bin/export stub for standards compliance, but it has no useful effect.

unset(1), env(1), printenv(1), set(1), declare(1), readonly(1), typeset(1), bash(1)

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