I use screen all the time and am constantly attaching/detaching from different sessions. Occasionally I'll accidentally logout/exit instead of detach, losing the buffer of my work on that project. I'd rather not have the detach (ctl-a ctl-d) and exit (ctl-d) commands be so close.
Is there a way to force screen to only ever detach instead of exit?
The main problem isn't screen, it's the shell inside of it. You can make it ignore Ctrl+D or handle it differently. For BASH, try
export IGNOREEOF=4
which means you'll have to press Ctrl+D 4 times to exit the shell.
See this question for more solutions: https://unix.stackexchange.com/questions/27588/how-can-i-keep-controld-from-disconnecting-my-session
Related
I am working on a Tcl project where a certain procedure will run continuously. user can abort that procedure anytime using some Key-Combination. So basically, I need to trap the signal within Tcl code. So far, everything is done except one problem.
I am using Ctrl+Z i.e. SIGSUSP signal (SIGTSTP in case of Tcl) which technically does the job.
signal trap sigtstp onAbort
But, pressing Ctrl+Z immediately returns the Shell prompt, rest of the output from the program comes after that and when output comes to an end, no shell prompt returned (as it is already returned before). I need to press Enter again to get the prompt.
Following is the case I am refering to. You can see the prompt (polaris#ubuntu:~$) is returned in between output of the main program.
Also as output of pressing Ctrl+Z, it returned [40]+ Stopped, which is bit annoying. Can I avoid this ?
Can I avoid this whole problem using some other key-combination i.e. signal ? Or can I avoid this with Ctrl+Z also by tweking something ?
NOTE: I have tried using Ctrl+C. I got the exactly expected behavior with that. Unfortunately I can't use Ctrl+C as it is used for some other functionality.
Cz causes the shell to send the current foreground process a SIGSTOP(19). This signal cannot be caught or ignored and so your program will receive it and run the default handler. This is not killing the process as your question suggests you're trying to do. This only suspends it and you can bring it back into the foreground using fg on most modern shells.
Looks like you're out of luck. However, you might be able to rebind the keychord at the level of the shell. This is outside your program though and your end users don't have control over it. (Cf. https://superuser.com/questions/378018/how-can-i-do-ctrl-z-and-bg-in-one-keypress-to-make-process-continue-in-backgroun)
Also, if your program relies on user inputs for various actions (since you suggest that C-c does something else), perhaps you should make it a full fledged CUI application using curses or something?
Is it possible to move a process from one terminal to another in Linux? For example, if I have executed the "top" command via a gnome-terminal window, I want to move the output shown in the gnome-terminal window to a TTY terminal.
It's too late by the time you've already executed it, but if you recognise in advance that you might want to move it, you can use
screen top
to run top, and then detach from the running process with Ctrl-A and D. After that, you can run
screen -r
from any terminal on the same machine to reattach.
It's very powerful, and does a lot more than just that.
I am on windows machine, when I temporarily change to console using :sh then back to vim with exit command and then again back to console and it starts over. this causes me to lose my previous directory. Is there other way returning back to vim won't start the shell over?
Not really
https://stackoverflow.com/a/12089631/1427295
GVIM does not retain a "handle" to the shell that launched it in a way
that allows it to send commands back to it. Because of they
synchronous execution, you also cannot launch a shell from GVIM, keep
feeding it commands while also continue working in GVIM.
I'm afraid you have to use the functionality of your window manager to
launch (and then later re-activate) a shell window, and send the
commands as keystrokes to it. On Windows, this can be done (e.g. in
VBScript) via WshShell's Run(), AppActivate() and SendKeys() methods;
there are probably similar mechanisms for window control on Linux,
too.
If you don't mind having that shell inside your GVIM (emulated, with
all its drawbacks), though, there are plugins that enable that.
https://serverfault.com/a/95405
The Windows command interpreter ("cmd.exe") doesn't provide any
support for saving/exporting/keeping history, of, if it does,
Microsoft didn't document it and nobody was ever able to find it. You
can of course try to work around that, like Sean suggested, but
there's (or does appear to be) no built-in support for this
You may be able to output your command history using echo %cd% > prev_dir.txt then create a script that cds to the directory in prev_dir.txt, but you'd still have to remember to save your directory to the file before you exit the shell each time.
I have a recurrent problem when using R with a Linux console. I sometimes suspend it with [Ctrl+Z], then put it to the background with bg, (execute some other commands), then put it to the foreground again with fg.
R resumes correctly with all the workspace intact, but when I type, the characters are invisible (just like when we type passwords).
I still can execute commands though, and I see the response. Moreover, when I type [enter], the prompt doesn't go to the next line, but does something like this: > > >.
Then I need to quit R using q(), in order that everything returns to normal. I didn't manage to find any reference to this problem on internet.
Would you have an idea? Thanks a lot for your help.
No direct answer but via
"Doctor, doctor, it hurts when I do this."
"Then just don't do this."
I would suggest that if you must have an R console open, place it inside screen --- or if you have it, byobu a fancier extensions, or even tmux.
Or even inside the One True Editor (TM) using ESS. For what it is worth, I always run emacs --daemon and then connect to the same R session either via emacsclient -nw on the terminal or under X11 via emacsclient -c (both of which I aliased to emt and emx). I also run byobu sessions for command-line work where I often use littler for command-line tasks and tests.
Unix is a multitasking system. There is no need to limit yourself to one prompt, especially if you suffer side-effects as a consequence.
I am using Putty to connect to a remote server. What I want to know is if there is any way to write my commands and allow them to keep running after I close the session with Putty. The reason for this is that I do not want to keep the computer ON all the time. Is there any way to do this?.
Update with the solution
For my question as it is presented the best solution is use one of the commands provided such as nohup, because you do not have to install any additional software. But if you are in the same problem use screen, install it and use it. It is amazing.
I have selected the answer of Norman Ramsey as favourite because propose several solutions using commands and screen. But please check the other answers specially the one of PEZ, then you get an insight of what screen is able todo.
screen! It's the best thing since sliced bread. (Yeah, I know others have already suggested it, but it's so good the whole world should join in and suggest it too.)
screen is like, like, ummmm ... like using VNC or the like to connect to a GUI destop, but for command shell windows. You can have several shell "windows" open at once in the same screen session. You can do stuff like:
Start a screens session using "screen -dR" (get used to using -dR)
run some commands in one window
press CTRL-A,C to create a new window open a file there in vim
press CTRL-A,0 to go back to the first window and issue some command on the file you just edited
CTRL-A, 1 to go back to your vim session
CTRL-A, C for yet another window and maybe do "sudo - su" (because you just happen to need a full root shell)
CTRL-A, 0 and start a background process
CTRL-A, C to create yet a new window, "tail -f" the log for that background process
CTRL-A, d to disconnect your screen then CTRL-D to disconnect from the server
Go on vacation for three weeks
Log on to the server again and issue "screen -dR" to connect to your existing screen session
check the log in the the fourth window with CTRL-A, 3 (it's like you've been there watching it all the time)
CTRL-A, 1 to pick up that vim session again
I guess you're starting to get the picture now? =)
It's like magic. I've been using screen for longer than I can remember and I'm still totally amazed with how bloody great it is.
EDIT: Just want to mention there's now also tmux. Very much like screen, but has some unique features, splitting the windows being the most prominent one.
nohup, disown, and screen are all good but screen is the best because unlike the other two, screen allows you to disconnect from the remote server, keep everything running, and then reconnect later to see what is happening. With nohup and disown you can't resume interacting.
Try using GNU Screen. It allows you to have several shells open at once. And you can disconnect from those running shells (i.e. close session with Putty) and they will keep doing their thing.
What you are looking for is nohup.
See the wiki link for how to use it.
screen is the best.
Try:
screen -dmS "MyTail" tail -f /var/log/syslog
This start command in background.
Use screen -r to list, and or screen -r Mytail to enter session.
If more users need access same session, use: screen -rx MyTail, and both or more users share the session.
If you can't use screen (because, for instance, your SSH session is being programmatically driven), you can also use daemonize to run the program as a daemon.
One way that works well for me is at.
at works like cron, but for a one-time job. I used it today to download a large file without having to keep my session alive.
for example:
$ at 23:55
at> wget http://file.to.download.com/bigfile.iso
at> ^D
You pass at a time (in the future) and it gives you a prompt. You enter the commands you want to run at that time and hit ctrl+d. You can exit out of your session and it will run the commands at the specified time.
Wikipedia has more info on at.
./command & disown
ssh localhost && ./command && exit