foreground background 1 user commands nosh foreground background execute two commands, sequentially or in parallel foreground --separator alt-sep left-prog ; right-prog background --separator alt-sep left-prog & right-prog foreground and background are chain-loading utilities that run left-prog as a child process created by fork3 and chain load to right-prog in the current process. Both are executed as if with the execvp3 function. left-prog and right-prog may contain their own command line options, which foreground and background will ignore. The --separator command line option specifies an alternative separator argument, to scan for in place of ; or &. foreground waits for the child process to finish before continuing in the parent, executing the programs sequentially. background runs child and parent in parallel, without waiting. The primary use of foreground and background is from a nosh1 script to enact command lists. When invoking foreground or background from within a shell script, remember that ; or & must be escaped or quoted in order to prevent the shell from recognizing it. The commands look for the leftmost instance of the separator ;/&, and separate left from right there. Further instances of the separator in right-prog are left alone. This allows longer lists, by using another foreground or background in right-prog. However, these commands are intended only for enacting simple sequential or parallel command lists. For more complex command lists, these are not the correct tools. Jonathan de Boyne Pollard