I'll be glad if someone can fix the title to be more appropriate since I'm pretty new to terminal.
I have an issue with terminal. Once I execute a command, if it goes to the next line, I can't close it or revert it. I assume it starts the executable or asks for more parameters using >
For example:
//Windows Machine
vagrant up
//Vagrant Instance Unix Machine
$ git
>
>
>
> ... it goes on like this, I can't close > so I can't execute other commands
The only solution on fixing is restarting the terminal (which means I need to restart Vagrant instance)
It happens on some commands only - not all, so I don't know what makes a difference.
For example, executing composer, I get information about Composer and terminal goes back to main state. However, if I execute things like php, git, mysql, > symbol appears and I can't return from there.
So, two basic questions;
What causes this?
How can I terminate the current command to go back main state?
Any help would be greatly appreciated.
Ps. I use both windows terminal and unix terminal and this issue happens on both.
Normally you'll see a > prompt if you've entered a command that's syntactically incomplete, for example if there's a unterminated string literal:
$ echo 'hello
> '
hello
$
It means that the shell is waiting for you to type the rest of the command, or at least enough of it to make for something that's not a syntax error.
In this example, the default prompt, $PS1, is '$ ', and the secondary prompt, $PS2, is '> '. Read the documentation for your shell (probably bash) for more information.
You can cancel the current command and get back to your primary prompt for a new command by typing Control-C.
This is all about the behavior of your shell; it has nothing to do with your terminal (almost certainly a terminal emulator), which merely provides a GUI for your shell to run in.
Related
I would like to configure my bash in a way so that I react on the event that the user enters a command. The moment they press Enter I would like my bash to run a script I installed first (analog to any PROMPT_COMMAND which is run each time a prompt is given out). This script should be able to
see what was entered,
maybe change it,
maybe even make the shell ignore it (i. e. make it not execute the line),
decide on whether the text shall be inserted in the history or not,
and maybe similar things.
I have not found a proper way to do this. My current implementations are all flawed and use things like debug traps to intervene before executing a command or (HISTTIMEFORMAT='%s '; history 1) to ask the history after the command execution is complete about things when the command was started etc (but that is only hindsight which is not really what I want).
I'd expect something like a COMMAND_INTERCEPTION variable which would work similar to PROMPT_COMMAND but I'm not able to find anything like it.
I also considered to use command line completion to achieve my goal but wasn't able to find anything about reacting on sending a finished command in this, but maybe I just didn't find it.
Any help appreciated :)
You can use the DEBUG trap and the extdebug feature, and peek into BASH_COMMAND from the trap handler to see the running command. (Though as noted in comments, the debug trap is sprung on every simple command, not every command line. Also subshells elude it.)
The debug handler can prevent the command from running, but can't change it directly. Though of course you could run any command inside the debugger, possibly using BASH_COMMAND and eval to build it and then tell the shell to ignore the original command.
This would prevent running anything starting with ls:
$ preventls() { case "$BASH_COMMAND" in ls*) echo "no!"; return 1 ;; esac; }
$ shopt -s extdebug
$ trap preventls DEBUG
$ ls -l
no!
Use trap - DEBUG to remove the trap. Tested on Bash 4.3.30.
I am not sure if this is possible but I couldn't find the answer anywhere else or even people who have tried it but my current PS1 is this:
export PS1="\[\e[00;32m\]??\[\e[0m\]\[\e[00;37m\]\n\[\e[0m\]\[\e[01;31m\]\d\[\e[0m\]\[\e[00;37m\] \[\e[0m \]\[\e[01;31m\]\T\[\e[0m\]\[\e[00;37m\]\n\[\e[0m\]\[\e[00;32m\]>\[\e[0m\]"
It is showing up and working upon opening the terminal however I am wondering if it was possible to clear the screen after a command finishes (with a prompt similar to windows cmd 'pause' command if possible) so that it isn't repeated or shown at the bottom of the window
I am running Manjaro XFCE if it makes a difference.
Thanks!
You can try something like this:
PS1='$(echo "(press enter to continue)" > /dev/tty ; read ; clear) $ '
NOTE: You need the redirect > /dev/tty because the standard output of the commands run by PS1 goes nowhere.
Replace the ending $ with whatever prompt you want to show.
I don't really think it is such a good idea. In the short time I've been testing that, it is so irritating!!!
I think you are way better just pressing Ctrl+L befor typing your command to clear the terminal.
I use the command xdg-open quite a lot in my Ubuntu Linux terminal. However, two things irk me:
Is it possible to suppress the error messages?
Is it possible to get the command to always complete? (That is, not continue running, so that I have another "new line" in my terminal).
I realize 2 may not be possible, because of the way the program works, but I imagine 1 is.
First one is easy. Just
alias xdg-open="xdg-open 2>/dev/null"
If you want it permanently, just add that line to ~/.bashrc file.
I recommend you to think twice if you want to become blind to errors, though.
The second one is quite confusing to me. xdg-open shouldn't be intereactive. In my computer (Debian sid) xdg-open execs the command and ends, even if the command itself has not ended (ie: you have not closed the application opened for the URL). I think this should be the behaviour of xdg-open on any platform (it's supposed to work exactly the same way on any XDG system, that's its very purpose).
Anyway, for any command you launch in a shell, if you want it to be non-interactive, that is, to allow to enter commands even if the previous one hasn't finished, you just attach "&" to the end of it. Example:
# prompt is not shown until you close the calculator
$ gnome-calculator
# prompt is shown right after opening calculator and you can
# work on the shell even if you don't close it
$ gnome-calculator &
I maybe late for the answer, but I got exactly the same problem like you have / had.
I tried to start a URL with xdg-open, my default browser is firefox, and not xdg-open but firefox started with an error:
[user#user-pc ~]$ xdg-open https://www.google.de # the page opens fine, but firefox had an error
[user#user-pc ~]$
(process:3783): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
# needed to press enter here
xdg-open closed fine but the firefox error stayed and I need to press enter to get the bash moving.
To get along this problem I called xdg-open within a new shell putting those output to /dev/null:
bash -c "xdg-open https://www.google.de" 2> /dev/null
The page opened fine, no error shown – rather nothing has been shown. And no need to press enter.
I have written a Fortran program (let's call it program.exe) with does some simulation for me. Via ssh I'm logging ino some far away computers to start runs there whose results I collect after a few days. To be up-to-date how the program proceeds I want to write the shell output into a text file output.txt also (since I can't be logged in the far away computers all the time). The command should be something like
nohup program.exe | tee output.txt > /dev/null &
This enables me to have a look at output.txt to see the current status even though the program hasn't ended its run yet. The above command works fine on my local machine. I tried first with the command '>' but here the problem was that nothing was written into the text file until the whole program had finish (maybe related to the pipe buffer?). So I used the workaround with 'tee'.
The problem is now that when I log into the computer via ssh (ssh -X user#machine), execute the above command and look at output.txt with the VI editor nothing appears until the program has finished. If I omit the 'nohup' and '&' I will not even get any shell output until it has finished. My thought was that it might have to do something with data being buffered by ssh but I'm rather a Linux newbie. For any ideas or workaround I would be very grateful!
I would use screen utility http://www.oreillynet.com/linux/cmd/cmd.csp?path=s/screen instead of nohup. Thus I would be able to set my program to detached state (^A^D) reconnect to the host, retrieve my screen session (screen -r)
and monitor my output as if I never logged out.
I am installing a virtualenv and want to understand what's going on.
$ curl -O https://raw.github.com/pypa/virtualenv/master/virtualenv.py
- I understand curl fine
$ python virtualenv.py my_new_env
- Understand this, too
$ . my_new_env/bin/activate
- Here's where I get lost. What is the period doing here?
(my_new_env)$ pip install ...
- What does it mean to have the parentheses here? Does this use tell me I'm in a folder?
The dot is a command that means to read and execute the contents of the given script in the current shell (normally running a shell script runs it in a new process.) Evaluating the script in the current shell can change the environment variables of the current shell, so the behavior of subsequent commands is affected.
I don't know for sure about the parentheses, but I don't think they're meant to be syntax you type. As they come before the '$' prompt, perhaps that's literally what you'll get as your new prompt after running the activate script, to show you that your environment has been changed?
The dot is essentially an "execute" command — execute the commands in my_new_env/bin/activate as though they were typed into your prompt, essentially.
The parentheses shown in the prompt (at least in the tutorial instructions) then indicate that you're typing commands in your new virtual environment, and not in your original (real) environment.