I am writing my first ever bash script, so excuse the noobie-ness.
It's called hello.bash, and this is what it contains:
#!/bin/bash
echo Hello World
I did
chmod 700 hello.bash
to give myself permissions to execute.
Now, when I type
exec hello.bash
My putty terminal instantly shuts down. What am I doing wrong?
From the man page for exec:
If command is supplied, it replaces the shell without creating a new process. If no command is specified, redirections may be used to affect the current shell environment.
So your script process runs in place of your terminal and when it exits, so does your terminal. Just execute it instead:
./hello.bash
Related
I have a shell script and I want the session text to be saved automatically every time the script runs, so I included the command "script -a output.txt" at the beginning of my script. However, the script stops running after this line of code, which only displays a "bash-3.2$" on the screen and won't go on. Any ideas?
Thanks in advance!
The problem is script starts a separate sub-shell than the one that is running the actual script, to club them together. Use the -c flag in script
-c, --command command
Run the command rather than an interactive shell. This makes
it easy for a script to capture the output of a program that
behaves differently when its stdout is not a tty.
Just do,
script -c 'bash yourScript.sh' -a output.txt
I have a VM that I want running indefinitely. The server is always running but I want the script to keep running after I log out. How would I go about doing so? Creating a cron job?
In general the following steps are sufficient to convince most Unix shells that the process you're launching should not depend on the continued existence of the shell:
run the command under nohup
run the command in the background
redirect all file descriptors that normally point to the terminal to other locations
So, if you want to run command-name, you should do it like so:
nohup command-name >/dev/null 2>/dev/null </dev/null &
This tells the process that will execute command-name to send all stdout and stderr to nowhere (instead of to your terminal) and also to read stdin from nowhere (instead of from your terminal). Of course if you actually have locations to write to/read from, you can certainly use those instead -- anything except the terminal is fine:
nohup command-name >outputFile 2>errorFile <inputFile &
See also the answer in Petur's comment, which discusses this issue a fair bit.
I have written a batch file like this:
Start putty.exe -ssh 172.17.0.52 -l root -m dummy.txt
Then in dummy.text I have written this command:
avahi-daemon --no-drop-root -D
export XVHMI_USERCONFIG_PATH=/home/UserProfileConfig
export XDG_RUNTIME_DIR=/tmp
cd /opt/bosch/airis/bin
When I run the .bat file, PuTTY starts, commands execute (hopefully, not sure) and it exits.
How to keep that window open?
I have googled for the same, but no solid help. I read on stack overflow itself that we need to define something in txt file, but what and most importantly how?
The SSH session closes (and PuTTY with it) as soon as the command finishes. Normally the "command" is shell. As you have overridden this default "command" and yet you want to run the shell nevertheless, you have to explicitly execute the shell yourself:
avahi-daemon ... ; /bin/bash
Also as use of -m switch implies a non-interactive terminal, you probably want to force an interactive terminal back using -t switch.
Though, I'm not really sure if you want to execute shell or if you just want to see your command output. If the latter, did you consider using plink? It's console terminal client from PuTTY package. Being console application, it inherits console of parent batch file, and you can pause the batch console from closing using pause command, if needed.
Another option (both for PuTTY and plink) is to pause on remote side. E.g. Using read command.
avahi-daemon ... ; read
As suggested by Martin I tried this step:
putty.exe -ssh 172.17.0.52 -l root -m dummy.txt -t
added /bin/bash at the end of commands in dummy.txt
It worked for me. Please note, you have to follow both the steps as mentioned above.
This way you can keep the session alive and can manually execute further commands.
ssh user#myserver.com<<EOF
cd ../../my/path/
sh runscript.sh
wait
cd ../../temp/path
sh secondscript.sh
EOF
The first script runs and asks me the questions in that script, but before i'm even able to start typing to answer them the second script starts running. From what I'm reading this shouldn't be happening even without the wait.
I'd like to run a script every time I close a Bash session.
I use XFCE and Terminal 0.4.5 (Xfce Terminal Emulator), I would like to run a script every time I close a tab in Terminal including the last one (when I close Terminal).
Something like .bashrc but running at the end of every session.
.bash_logout doesn't work
You use trap (see man bash):
trap /u1/myuser/on_exit_script.sh EXIT
The command can be added to your .profile/.login
This works whether you exit the shell normally (e.g. via exit command) or simply kill the terminal window/tab, since the shell gets the EXIT signal either way - I just tested by exiting my putty window.
My answer is similar to DVK's answer but you have to use a command or function, not a file.
$ man bash
[...]
trap [-lp] [[arg] sigspec ...]
The command arg is to be read and executed when the shell
receives signal(s) sigspec.
[...]
If a sigspec is EXIT (0) the command arg is executed on
exit from the shell.
So, you can add to your .bashrc something like the following code:
finish() {
# Your code here
}
trap finish EXIT
Write you script in "~/.bash_logout". It executed by bash(1) when login shell exits.
If you close your session with "exit", might be able to something like
alias endbash="./runscript;exit" and just exit by entering endbash. I'm not entirely sure this works, as I'm running windows at the moment.
edit: DVK has a better answer.