The shell interprets the string. If the exit status from the command is 0, the action is considered successful. User and group IDs are set to the recipient's IDs. Working directory is the recipient's directory. The value of the umask variable is 0077.
Standard input is set to the message.
All other file descriptors are closed. After that time, the process is terminated. If the exit status of the program is 0, it is assumed that the action succeeded. Otherwise, the action is assumed unsuccessful. Acts similarly to pipe , but executes the command directly after built-in variable expansion without assistance from the shell.