Use Case 1: user command/script synchronization

The first use case is very simple: you don’t want some commands or some scripts submitted by a user can run at the same time. The typical usage is related to crontab and the chance some command runs late due to an undesired condition.

Open two terminals and try this experiment:

1. inside the first terminal write this command at prompt, but do not press “enter”: “flom -- ls”
2. inside the second terminal write this command at prompt: “flom -- sleep 10”
3. now press “enter” key at the second terminal (where you have written “flom -- sleep 10”)
4. switch to first terminal and press “enter” key

Expected result:

1. the second terminal pauses for 10 seconds
2. the first terminal pauses and displays the output of command “ls” after the second terminal sleeping terminates

Terminal 1 output:

tiian@mojan:/usr$ flom -- ls
bin  games  include  lib  lib64  local	sbin  share  src
tiian@mojan:/usr$ 

Terminal 2 output:

tiian@mojan:~$ flom -- sleep 10
tiian@mojan:~$ 

Explanation:

command “sleep 10” and command “ls” synchronized: “ls” executed after “sleep 10” completion. flom command protects (synchronizes) the execution of the command (or script) specified after the -- separator on the command line.

Summary

The simplest usage form of command flom allows you to synchronize commands/scripts on a per user basis (synchronization does not happen between commands/scripts executed by different users).