In the past, I've used
nohup to run big background jobs, but I've noticed that a lot of people use
screen in this context. Does
screen provide some kind of functional advantage that I am unaware of, or is it just a matter of preference?
In the past, I've used
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Both have there own + and - :
- nohup is good to use for running procs in background when proc don't need any user input like HTTPD server or any other server proc like that.
- nohup does create log in dir of proc execution. log file name
- It avoids proc getting killed due to mistaken
ctrl+C , ctrl+D. Just a safe guard.
- It's normally installed by default with basic setup. No need to install separately like screen.
- It's functionality is very specific to running a job in background and dumping output. Low memory intensive.
- Got to install separately. You can go to a data center or login to
any box and expect screen is present.
- Good to manage multiple terminals on separate subjects and give them name.
- Its more of terminal manager and not a command to run a proc for infinite time like nohup.
- It's more suitable if proc need user input. Like install
scripts, yes/no prompts.
- With tones of features, comes it's memory. But agreed, some are really great features.
@rahmu, I will never guess pid if want to kill it. Be sure before killing someone/something ;) .
Best way in both cases for screen and nohup is:
ps -eaf | grep "nohup" | grep "your proc name/keyword" .
Use screen and check what is running on it.
To conclude, both are two different things made with different agendas so comparison is difficult.
screen has a ton of features. It doesn't just "daemonize" a process, it's more of a window manager for terminals.
It can be used if the process needs input at some point, you can go and check the process's output, reconnect to its terminal, ...
So no, it's not just a matter of preference, they are not the same thing at all.
screen lets you:
- come back to the actual running screen, send signals, see how fast it goes, see whether there are error messages etc..
- name processes with a meaningful title. if you want to kill one process you don't have to do a guess work about its process id.
- process progress can be checked also by
nohupby database fields debug.
ps ax | grep nohupwill show you the id of the process and you can kill it.
nohupis faster. The simple reason is that it depends on the internet connection between your PC and the server. Whenever the internet goes slow, the process goes slow as well.