Bash - check environment variables

Question

The env command can be used to print environment variables in bash. I want to ask if there is any built-in command to do this ?

$ export temp="hello world"
$ env | grep temp

The second command will indeed print temp's value, but that's because it is inherited as environment when env was spawned. I want to check what environment variables the bash shell process had originally, in which temp would still not be part of environment , but just marked to be exported as environment for any child (I want to test this).

Answer 1

You are right. When exporting or declaring a variable inside a shell, the variable is not added to the shell's environment (in the mean of updating the file - read below).

You can view the environment variable the shell (or any other process) had when it was invoked on Linux by viewing the file /proc/PID/environ, where PID is the PID of the process you want to analyze. The variables are saved in the classic form var=value and are separated by the null character.