printenv

Printenv is a standard Unix utility that prints environment variables for the current process. It reads the process’s environment and outputs lines in the form NAME=value. When invoked without arguments, printenv prints all environment variables; when given one or more names, it prints only the values for the specified variables that are defined.

Usage and behavior: The syntax is typically printenv [NAME]... If a requested NAME is defined, printenv outputs NAME=value. If a requested NAME is not defined, nothing is printed for that name. Each variable is typically printed on its own line. The command does not modify the environment; it only displays it.

Common usage and examples: printenv PATH prints the search path used by the system to locate executables. printenv HOME prints the user’s home directory. Combined with other utilities, it is often used in scripts, for example to extract a specific variable or to filter output with grep (printenv | grep VARIABLE).

Implementation and scope: Printenv is commonly included in the GNU coreutils package on Linux and other Unix-like systems. It is not a shell built-in in most environments; it is a separate program that reads the environment of the running process. A related utility, env, can run a command with a modified environment, whereas printenv simply prints the existing environment.