Connected to my box via Putty.exe
$ tmux list-clients
/dev/pts/2: 1 [80x24 xterm-256color] (utf8)
/dev/pts/9: 1 [94x30 linux] (utf8)
$ tmux detach-client -t /dev/pts/2
the terminal flashes resizing the window to the full 94x30 for a moment
and then immediately resizes it back to 80x24
$ tmux list-clients
/dev/pts/2: 1 [80x24 xterm-256color] (utf8)
/dev/pts/9: 1 [94x30 linux] (utf8)
You need to disconnect the remote client, which is attached using a smaller window. You may be able to use the Byobu hot-key Alt-F6, or run /usr/lib/byobu/include/tmux-detach-all-but-current-client
Full disclosure: I'm the author and maintainer of Byobu.
Related
I have a application that launches xterm and dumps uart logs. I am able to see it launch and dump the logs in the GUI. However, Using a remote session I want the xterm output to be running as a background process somewhere so that I can switch back and forth within a single terminal.
Using GUI
Using remote terminal (SSH)
$ xterm
xterm: Xt error: Can't open display: :0
I tried to do something like, but failed to work -
alias xterm="/bin/bash -c"
I don't want to have X forwarding and launch a window on my local machine as well.
If you just need the logs, you most likely don't need an X server or xterm.
You can simply run the target command itself. From your screenshot it looks like the command might be telnet 127.0.0.1 <port_number>. You can find it from the script that your application launches, or with ps -ef when it's running. If it's an UART, then you can also use minicom or socat to connect directly to serial port without any extra programs. This way, you don't even need telnet.
You can combine this command with either screen or tmux so that it's running in the background and you can switch to it from any terminal or console. Just run screen with no arguments, then run the command on virtual screen. Detach with CTRL-a d, and your command will continue to run in the background ready for you to reconnect to it at any time with screen -r.
Moreover, screen can also connect to serial port directly so you get two for the price of one.
The thing with xterm is that it will not write the logs anywhere except in the graphics buffer, and even there it will be only as flashing pixels which is not suitable for any processing. If you insist on going that way, you have several options:
Change the script that application runs (might not be possible depending on your situation)
Replace /usr/bin/xterm with your dummy script that just runs bash instead of xterm, and redirects the output to a file (ugly, but you could probably avoid breaking other applications by changing PATH and putting it somewhere else). In your script, you can use bash's redirection features such as >, or pipe output to tee.
Start a VNC server in the background and set the DISPLAY environment variable when you run your application to the number of virtual screen. In this case, any windows from application will open on VNC virtual screen and you can connect to it as you please.
Use xvfb as a dummy X server and combine it with xterm logging, etc.
Solution 1: Fake xterm on X11-less systems
You can also create a wrapper script that replaces xterm with another function. Test this out on a laptop with X11:
$ function xterm {
echo "hello $#"
}
$ xterm world 1
hello world 1
$ export -f xterm
$ /bin/xterm # opens a new xterm session
$ xterm world 2 # commands executed in second terminal
hello world 2
This means that you've replaced the command xterm for a function in all of the child processes.
Now, if you already know that your script will work in a terminal without xterm, you could create a function that accepts all of the parameters and executes it. No need for complicated screen stuff or replacing /usr/bin/xterm.
Solution 2: Dump UART data for the winz
If you want to save all of the uart data into a file, this is easily fixed by creating a screen session and a log file. Below the command will create a session named myscreensessionname that listens on the serial connection /dev/ttyUSB0 and writes its data to /home/$USER/myscreensessionname.log.
$ screen -dmS myscreensessionname -L -Logfile /home/$USER \
/myscreensessionname.log /dev/ttyUSB0 115200
Note that if you're going to use multiple screen sessions, you might want to use serial ids instead of /dev/ttyUSB0. You can identify the connections with udevadmin as follows.
$ udevadm info --name=/dev/ttyUSB0 | grep 'by-id'
S: serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0
E: DEVLINKS=/dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0 /dev/serial/by-path/pci-0000:00:14.0-usb-0:4.4.4.1:1.0-port0
Here, instead of /dev/ttyUSB0, I would make use of /dev/serial/by-id/usb-FTDI_TTL232R-3V3_FTBDBIQ7-if00-port0.
EDIT:
You can attach the screen session with the following command. Once in the screen session, press crtl+a, and press d to detach.
$ screen -Dr myscreensessionname
To view all of your screen sessions:
$ screen -list
There is a screen on:
2382.myscreensessionname (04/02/2021 10:32:07 PM) (Attached)
1 Socket in /run/screen/S-user.
While writing code inside a tmux session, I inadvertently pressed a sequence of keys that has made my status bar disappear.
I haven't touched my tmux config file, and I verified the status bar is visible in new tmux sessions. Disconnecting and reconnecting to this session didn't help.
Read through the man page and searched through Google, no luck so far.
Running the following commands from inside the session didn't help:
^B :set-option -g status-bg default
^B :set-option -g status on
I have many windows open and would prefer not to have to destroy this session. Any help would be appreciated.
From the tmux command line, issue:
:set status on
to turn the status bar on. You can simplify this by adding a line to your .tmux.conf:
# toggle statusbar
bind-key b set-option status
and then reload your config.
Not quite a solution, but a possible workaround.
I'll assume your old session is number 0; adjust the argument to -t as necessary.
tmux new-session -t 0
This creates a new session which has all the same windows as session 0. If you create a new window in one session, it appears in the other as well. If you delete a window from one, it is removed from the other. More importantly, the new session should have a status bar. Then, you can try removing the old status-free session:
tmux kill-session -t 0
This should not affect the windows in session 0, since they are all part of your new session as well.
I help maintain a large number of Unix-like servers, and so keep a script called tmux-rebuild that I use to rebuild all the tmux sessions and windows with SSH links to each server.
I have tmux configured to show the window's name in red with an exclamation mark in its status bar when a terminal bell character is printed in that window. This is very handy for programs like irssi alerting me to when I have messages in another window.
I also have my $PS1 set up on every server to print a terminal bell at the end of every prompt. This is useful because if I run a long job in one window and switch to another, I can immediately see when it's finished because when my prompt is written to the screen after the job is done, tmux makes the window name come up in red with an exclamation mark. This is great for my workflow.
However it causes a slight problem with the rebuild script mentioned above, because when I start up tmux after running it, every window in every session is flagged in red, due to the first prompt being printed to the screen. This makes the feature useless until I visit every window, and there are something like 40-50 of them.
Is there something I can add to my script that will clear all alerts from sessions and windows after they are created? I don't mind using a kludge if necessary.
From the tmux man page, specifically the last sentence here:
kill-session [-aC] [-t target-session]
Destroy the given session, closing any windows linked to it
and no other sessions, and detaching all clients attached
to it. If -a is given, all sessions but the specified one is
killed. The -C flag clears alerts (bell, activity, or
silence) in all windows linked to the session.
So, simply:
tmux kill-session -C
Figured out an acceptable workaround; I redefined the next/previous bindings to allow repeats:
# Allow repeats for next/prev window
bind-key -r n next-window
bind-key -r p previous-window
This allows me to quickly sweep up the alerts for all windows in a session by pressing my prefix key and tapping "n" until they're all clear, and I'm back in my original window.
With tmux 1.6 (and later), list-windows can generate customizable output, so it is fairly simple to read the output lines and make a loop that runs select-window for each window.
Add list-session (to loop over all sessions, optionally), and display-message (to parse session specifiers, and to record the current/“last” windows so they can be properly restored), and you might end up with something like this:
#!/bin/sh
# usage: tmux-select-each [session [...]]
#
# Select every window in specified session(s). If no sessions are
# specified, process all windows in all sessions.
#
# This can be handy for clearing the activity flags of windows in
# freshly spawned sessions.
if test $# -gt 0; then
for session; do
tmux display-message -p -t "$session:" '#S'
done
else
tmux list-sessions -F '#{session_name}'
fi |
while read -r session; do
active_window=$(tmux display-message -p -t "$session:" '#S:#I')
last_window=$(tmux display-message -p -t "$session:"\! '#S:#I' 2>/dev/null)
tmux list-windows -t "$session" -F '#{session_name}:#{window_index}' |
while read -r window; do
if test "$window" = "$active_window" ||
test "$window" = "$last_window"; then
continue
fi
tmux select-window -t "$window"
done
if [ -n "$last_window" ]; then
tmux select-window -t "$last_window"
fi
tmux select-window -t "$active_window"
done
We have an attended-upgrade script which launches apt-get update && apt-get upgrade simultaneously on all our administered systems. Ideally, we'd want to launch them all inside a screen session. When I do it like this:
File: upgrade.sh
for host in $ALLHOSTS
do
some_commands_which_take_considerable_time
screen -X screen sh -c "ssh $host \"apt-get update && apt-get upgrade\""
done
$ screen ./upgrade.sh
, it works, but as there are new windows arriving on the session, they are automatically being switched to. Instead, I'd rather have a version where the active window is fixed unless contained process quits or I switch manually using ^A n.
Bonus points if there is a possibility to preserve windows with exited processes, but keeping them separate from windows with active processes.
You can do this with tmux. For example:
# Start a session named "apt-get" and leave it running in the background.
tmux session-new -d -s apt-get
# Preserve windows with inactive processes.
tmux set-option -t apt-get set-remain-on-exit on
# Start a new window without switching to it. You can also do this from
# within a running tmux session, not just outside of it.
tmux new-window -d -t apt-get -n upgrade-$host \
"ssh $host 'apt-get update && apt-get upgrade'"
Note that you can have multiple windows with the same name, or modify the argument to the -n flag for unique names. The tmux application doesn't care.
As an example, you could name each window "upgrade," but that would make it difficult to identify your SSH sessions at a glance. Instead, this example appends the value of the host variable (populated by your for-loop) to each window name. This makes it easier to navigate, or to programmatically close windows you are no longer interested in. This is especially valuable when you have a lot of unclosed windows displaying terminated processes.
Overall, the syntax is a little cleaner and more intuitive than GNU screen's for this sort of task, but your mileage may vary.
W/r/t preserving windows after a subprocess exits, one possibility is to invoke the zombie command in your screen config file(s), which requires that you specify two keyboard characters that kill or resurrect the window, respectively. E.g.:
zombie KR
Then, K would kill a window whose subprocess has terminated, while R would attempt to relaunch the subprocess in the same window. Note that, in a zombie window, those keys are captured at the top level (i.e., do not precede them with your normal screen control character prefix sequence).
In order to prevent automatic switching to a newly created window, try altering your invocation of screen to something like the following:
screen -X eval 'screen sh -c "ssh $host \"apt-get update && apt-get upgrade\""' 'other'
Thanks to CodeGnome, I'll probably go with tmux as I believe there is no way to do it with screen (that's unfortunate, really!).
To give a better sketch of how it can be used:
#!/bin/sh
tmux new-session -d -s active
tmux new-session -d -s inactive
tmux set-option -t active set-remain-on-exit on
for host in $ALLHOSTS
do
tmux new-window -d -t active: -n upgrade-$host "
./do_upgrade_stuff.sh $host
tmux move-window -s active:upgrade-$host -t inactive:
"
done
I have two xterms and several gnome-terminal windows active on my X display.
However, xlsclients only shows one gnome-terminal client.
$ xlsclients
luban.local /usr/X11/bin/xterm
ohm gnome-terminal
luban.local xterm
How can I get a list of the gnome-terminal sessions attached to my display?
This option will run the new terminal window in its own process and as a distinct X client.
--disable-factory
These options
--instance=foo --class=bar
provide a convenient hook to distinguish between sessions:
$ xlsclients -l
...
Window 0x3000001:
Machine: ohm
Name: Terminal
Icon Name: foo
Command: foo
Instance/Class: foo/bar
This is correct; gnome-terminal (like konsole) starts just a single process. If you ask for a second console, the process opens a new window but doesn't start another process just for that window (unlike xterm). This saves a lot of memory and resources.