Let say, I access to a server using ssh. In the same time, there is another person accessing that server.
Is it possible to watch what is going on in that person's terminal. Meaning, Can I just watch what he is typing?
If the other person is using the Linux console, you can use conspy.
If you mean that the other person wants you to see his console, you two can use screen to share a terminal. See http://www.gnu.org/software/screen/manual/html_node/Multiuser-Session.html for a full description of how to do it.
I also use an approach similar to what Maze said. This is a unidirectional sharing with read-only for the guest. This is how it works:
1) The host starts the script command writing somewhere where the guest has read access and set the permits as required, for example:
$ script -f /tmp/shared_screen
Script was started....
$ chmod 640 /tmp/shared_screen
$ chgrp shared_group /tmp/shared_screen
The -f flushes the contents permanently so you'll have a very low delay
2) The guest starts dumping the content of the file:
$ tail -f /tmp/shared_screen
In this case -f causes tail to wait on more output from the file. Use ctrl-C to stop displaying the file contents.
You can use the small tool script for logging the terminal into a file. The observing party can simply tail -f that file to follow.
This is a much simpler approach, but it works very nicely for most cases
To capture what Alice types in a terminal,
and then the next day let Bob see what was typed --
without any risk of Bob accidentally typing anything into that terminal --
Alice can type "showterm" ( http://showterm.io ) in her terminal window to start the recording.
To share a terminal so Alice and Bob both see "the same" terminal window and can both type commands into that window,
there seems to be three popular methods:
Byobu, tmux, or screen.
(tmate is a fork of tmux that works just as well, perhaps better).
"How to Share a Terminal Session with Friends" (with Byobu)
"Sharing Terminal Sessions With Tmux And Screen"
"ask Ubuntu: Share SSH Session at login"
"Remotely Working Together on a Terminal Session in Linux" (with screen)
Ubuntu: "HOWTO: Connect to another user's console terminal using 'screen'"
"HowTo Share A Terminal Session Using Screen"
Something nice and easy:
watch -n 1 cat /dev/vcsa1
watch -n 1 refers for the time to refresh.
You can also try "cat /dev/vcsa1"
Well depending on whether its for 'live' or 'ondemand' purposes, you could replay it online with a service like www.playterm.org.
If you want to share a session on a machine behind a firewall or NAT, you can use the open-source terminal sharing program Termbeamer.
Related
I am attempting to programmatically read the output written by an application running in a specific tmux pane, so that I can determine when to send-keys to it from a controlling process.
In particular, I would like to automatically enter a password, but I do not want to enter it until I am sure the password prompt has appeared.
My current attempt has been to use tty to find the controlling tty, and then pass it to pyserial to try to read, since it appears to be able to read tty's. Note that in the real application, I have other ways of finding out the tty.
Unfortunately, as soon as I run the following code, the target tmux pane immediately closes.
import serial
ser = serial.Serial('/dev/ttys013', timeout=1)
Is it possible to read from a pty this way?
I am running on OSX, but would appreciate a solution that works on both Linux and OSX.
Typically, with python you would use pexpect to start the program and interact with it via a pty, but if you already have a program running in tmux you could simply use tmux's pipe-pane command to save a copy in a file of what is written to the screen. For example, for a pane number 1 you can give the shell command:
tmux pipe-pane -t 1 'cat >/tmp/capture'
and then tail the file /tmp/capture. (Use tmux pipe-pane -t 1 to stop).
To avoid polling, you can use a fifo instead.
I have to connect to a linux server from my own Ubuntu machine and operate directly on the server.
A dozen of folder names are listed in a LIST file. How to write sth. (like a bash script?) to carry out the following procedures?
for fold_name in LIST {
/******on my own Ubuntu*******/
-- open 2 new tabs of prompt terminal
-- run an ssh command in both
-- then input passwd and log in automatically in both
/******on the linux server*******/
-- cd to directory xxx/fold_name in both
-- run aaa.exe in 1st tab
-- vim sth in the 2nd tab
}
Once the loop of open-tab-login is solved, I guess the second part is routine as simple bash script except that I don't know how to specify between 2 tabs, either.
The point is I want all tabs in the same terminal. To this end, manually, I often Ctrl+Alt+T to create a prompt and Ctrl+Shift+T to open many tabs within it. And ssh...cd...... in each one. You see how annoying and cumbersome it is!
There are a few things you might like to research, which will get you a little closer.
You can run an ssh without a password, if you use an ssh key. Check out ssh-keygen, and the -i option in ssh.
Opening up tabs in gnome-terminal can be done via the method described here: Open a new tab in gnome-terminal using command line
You can run specific commands (e.g. aaa.exe) on a remote box over ssh, by including the command after the ssh: ssh user#remotehost aaa.exe.
If you want multiple commands, try enclosing them in quotes: ssh user#remotehost "cd /xxx; aaa.exe". Vim does not need to be in the directory in question in most cases: ssh user#remotehost vim /xxx/filename"
If you want to do something interactive (like vim), include the -t flag in ssh.
The tabs will be independent of each other - I'd probably run half of the command in one window, the other (e.g. runnning aaa.exe in one window, using one command, and the vim in another window, using another command, that I just happen to run at the same time. This way I can resize the windows, and arrange them relative to each other, and see both at once.
-- open 2 new tabs of prompt terminal
This depends on which desktop you're using. For gnome, gnome-terminal takes the -e option to specify the script to execute in the new terminal window. So, for something like this, you would execute gnome-terminal -e $script &, placing each instance of gnome-terminal in the background.
If you're using a different desktop, other terminal applications typically have a similar option. So, you'd point the terminal application to a script that's going to run in the terminal, and complete the rest of your task for you.
-- run an ssh command in both
-- then input passwd and log in automatically in both
This is going to be more complicated. The classical solution is the expect utility. There might be other similar tools that do similar things, but expect is pretty much the usual way these kinds of things have been done in the past. When it comes to trying to automate an interactive application, expect is really the only way to go. Unfortunately, expect uses a somewhat arkane syntax, that first-time users typically find confusing, and hard to understand. I grumble, every time I see no other alternative but to use expect to automate something, but this is pretty much the only option that's usually available.
I'm using this very simple .screenrc:
logtstamp on
logfile /tmp/screenlog-%S.log
I tried launching screens with these two methods:
screen -L -S testing
screen -S tester -L
but the filename used is /tmp/screenlog.0S.log. What am I doing wrong? Using Screen version 4.00.03jw4 (FAU) 2-May-06, and according to the manual I should be able to name the log file using the session name
If you look at the man page (man screen) for your (8-year-old?) version of screen, you'll see it's missing the %S specifier. They must have added it since your version. I'm not sure why Ubuntu 12.04 shipped screen from 2006..
P.S. I'd advocate looking into tmux. It's a little bit harder to learn, but a lot more flexible: You can move windows between sessions, You can see multiple windows at once, You can nest sessions inside of other sessions, etc.
Also, if you are just looking to log the output of long-running processes, take a look at nohup.
Say for example, to open multiple instances of gedit editor I wrote a shell script like this-
gedit&
gedit&
gedit&
gedit&
But after I ran my shell script ./example.sh, I can find only one instance of gedit! I've even used the & operator, so that the shell doesn't wait for one instance to finish. Still I cannot see four instances of gedit.
Also I tried directly from the command prompt. If I just enter gedit& on the command line, it showed 1906 ( this is the PID of the newly created gedit process ), started one new gedit instance and returned to prompt again. When I typed gedit& on the command line, it showed 1909 this time, but no new instance of gedit! And I couldn't find any process with PID 1909 in the System Monitor too. Where did this new process go away?
Is the happening specific to gedit? If so, what is the generic behavior when creating multiple instances of a program?
It is specific to gedit. You are likely looking for gedit --new-window &.
From man gedit:
--new-window
Create a new toplevel window in an existing instance of gedit.
I came here, trying to start multiple instances of audacious.
Allowing only one instance is actually harder to implement, because the program needs to find and communicate with the instance already running. This is done via D-Bus. In order to prevent communication with the already started instance you can run the program in another D-Bus session:
nohup dbus-run-session audacious &
nohup dbus-run-session audacious &
Note: nohup will keep the program running even if the terminal is to be closed.
This method should also work for other programs which do not let the user choose between multiple instance vs. one instance.
Beware that this might introduce bugs, if multiple instances are accessing the same configuration files.
Tested with xfce 4.14.1 and dbus 1.12.20
For Scite:
scite -check.if.already.open=false &
A word of caution:
If you, like me, have your system running for multiple months and have edited some of your shortcuts or aliases to open with this hack, then after a while some programs will not start anymore because there are already too many open D-Bus session. In this case you have to kill the started D-Bus sessions, which do not close when the started program closes. The other way around, killing the D-Bus session, will also kill the opened program, so use with care! For me personally, I have some long running autostarted programs which I want to keep open (firefox), so I kill all but the first 10 D-Bus sessions with this:
for pid in $( ps --sort start_time -aux | grep dbus-daemon | tail +10 | awk '{ print $2; }' ); do kill $pid; done
The cleanest solution would be to write a launcher script which waits for the program to finish and then closes the opened D-Bus sessions. But this is a bit more difficult than it seems because it is hard to find the PID of the corresponding D-Bus session.
P.S.: I also used this hack because there seems to be some program on my system which, after a while, slows down the system's default file open dialog to take multiple minutes if not longer to open! Programs then seem to hang when trying to save or open files. A new D-Bus sessions seems to fix this for some reason. While writing this, I found that pkill gvfsd-trash also works and that it may have been this bug. So until this gets shipped, I guess I'll add pkill gvfsd-trash to my crontab.
This seems specific to gedit, perhaps there's some option to turn off the check for a running instance.
Looks like gedit is first looking for a running instance and simply ignores further start-requests (just a wild guess). But the manual page says, that you can open another window:
--new-window
Create a new toplevel window in an existing instance of gedit.
That wouldn't exactly solve your problem, but maybe that's what you were looking for in the first place.
Good luck,
Alex.
Using this in a script. I've found that it does what I need it to:
#!/bin/bash
xterm -e "gedit; bash" &disown
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