I'm defining something like this in my crontab:
* * * * * ssh -tt otherhost whoami
And I'm getting the following output:
tcgetattr: Invalid argument
me
Running ssh with fewer -ttoptions leads to other errors besides tcgetattr.
The solution posted in why is the `tcgetattr` error seen when ssh is used for dumping the backup file on another server? doesn't really work well because in this case I'm using several ssh connections to run monitoring scripts on different hosts and I need to capture output sent to stderr and email it.
Any ideas on how to workaround this?
You could use something like this:
ssh -tt otherhost "your_monitoring_script 2>&1" 2> /dev/null
That way the errors from ssh go in the bucket, but the errors from your script are shown in stdout. For that to work you should mark errors from your script as "ERROR:" so that you can find them back if your script provides lots of output.
Related
I am trying to run the command while looping through
a series of sever addresses.
while read server
do
ssh -t $sever "sudo md5sum $fileName >> hashes"
done < serverNamesFile
within a script in bash but i keep getting this error
sudo: sorry, you must have a tty to run sudo
if I run the same line of commands in the command line though, it works perfectly fine.
Can someone tell me why this keeps happening?
you probably have
Defaults requiretty
in your /etc/sudoers file.
As the option's name suggests, that will cause sudo to require a tty
I solved my problem. apparently looping through a series of servers inside a script causes the "TTY" error for SSH.
a better practice is to create a script that takes in the address of the server you want to SSH in and then pass in the commands that way. you can still loop through a series of file or commands by calling SSH each time and use this command:
while read stuff
do
ssh -qtt $severName " command"
done < $fileStuff
I have this easy script for checking connection of specific interface with one condition.
If interface exists do nothing, if not dial VPN
#!/bin/bash
FOUND=`grep "tap0" /proc/net/dev`
if [ -n "$FOUND" ] ; then
echo yes
else
openvpn /home/pi/vpn/data/bezpasaka.opvn > /home/pi/vpn/errors.txt
fi
When I execute that it is working.
I also needed to add in into crontab so
*/1 * * * * /home/pi/vpn/checkvpn.sh
It supposed to work, I tried different bash with mkdir only and it was working fine.
Cron execute checkvpn.sh (i can see that in processes using :
ps ax | grep 'checkvpn.sh'
The problem I think is, that after cron execute checkvpn.sh it dials VPN and it gooooes all to the end until it cancelled whole connection because he can't hold the session probably. Atleast that what I though after checking errors.txt file
Have you any idea about any solution?
openvpn /home/pi/vpn/data/bezpasaka.opvn > /home/pi/vpn/errors.txt
where does openvpn located? when the cron get executed it does not normally loads PATH variables and hence does not know how to execute openvpn. You need to give full path of openvpn like /usr/bin/openvpn in order for this to work.
also please check whether openvpn requires tty or not
I'd like to create a bash script to automatically connect myself to a bunch of servers, execute some commands there and save the output of these commands in one logfile on the server I use to connect myself to all the other servers.
So far I was able to create a logfile on each of the servers I'm connecting myself to or to display the output of each of the commands on the console of the server I use to get to all the other servers.
My script currently looks like this (I know about for loops, but I don't want to use them in this case because I need to execute different commands on each server):
#!/bin/bash
ssh server1 <<EOF
hostname
printf '\n'
mount
EOF
printf '\n'
printf '\n'
printf '\n'
ssh server2 <<EOF
hostname
printf '\n'
mount
EOF
...
My idea was to use the &>> operator, because I need to know if all commands where executed successfully or not. In the end I'd like to have only one logfile which should look somewhat like this:
server1
output of mount
server 2
output of mount
...
So, how can I manage to create only one large logfile that contains the results of all executed commands? Also, will this script still work correctly if I make use of the ssh -T option to get rid of the message "Pseudo-terminal will not be allocated because stdin is not a terminal."? And do I have to escape special characters like / _ - when using mount in my script to mount something?
Thanks in advance!
I suggest using Open source utilities like logstash or fluentd.
I would use fabric, which is a tool to interact with several servers using ssh. It provides operations for executing remote shell commands.
For your example, the fabfile:
from fabric.api import run, sudo
def my-task():
run('hostname')
run('mount')
An you can execute it:
fab -H server1,server2 my-task
Output will be via standard output of the server you are executing so you can easily redirect it to a file:
fab -H server1,server2 my-task | my-task.log
I have a web server (odin) and a backup server (jofur). On jofur, I can run the following code to rsync my web directories (via key authentication) from odin to jofur:
rsync -avz -e ssh backups#odin.mydomain.net:/home/backups /home/myuser/odin
If I enter this into the command line, everything rsyncs perfectly:
myuser#jofur:~$ rsync -avz -e ssh backups#odin.mydomain.net:/home/backups /home/myuser/odin
receiving incremental file list
sent 23 bytes received 1921 bytes 1296.00 bytes/sec
total size is 349557271 speedup is 179813.41
I want this to run every morning, so I edited my crontab to read this:
0 4 * * * rsync -avz -e ssh backups#odin.mydomain.net:/home/backups /home/myuser/odin
This doesn't work. The following message is deposited in /var/mail/myuser:
Could not create directory '/home/myuser/.ssh'.
Host key verification failed.
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: unexplained error (code 255) at io.c(605) [Receiver=3.0.9]
I'm not sure what this error means. I'm wary of futzing blindly with permissions because I don't want to leave any backdoors open. Any suggestions?
Its hard to tell whether cron is using the wrong rsync binary or whether rsync requires some variable which is not being set in cron. Please set the stdout/stderr as shown below and pass on the output of the log file
Also, try doing a "which rsync" from the command line ; this will tell you which rsync you are using from the command line.
0 4 * * * rsync -avz -e ssh backups#odin.mydomain.net:/home/backups /home/myuser/odin > /tmp/cron_output.log 2>&1
EDIT :
Can you create a shell script called SOME_DIR/cron_job_rsync.sh which contains the following. Make sure you set the execute bit.
#!/bin/sh
/usr/sbin/rsync -avz -e ssh backups#odin.mydomain.net:/home/backups /home/myuser/odin
And modify the cronjob as shown below
0 4 * * * SOME_DIR/cron_job_rsync.sh >/tmp/cron_output.log 2>&1
I had a similar issue. Mine was the HOME directory was encrypted.
If your user is logged, it works the known_hosts.
But when it's a cron, the cron uses the right user BUT it does not have access to your $HOME/~/.ssh directory because is encrypted :-(
i got the same error just like you.
I finally found user home directory is an 'mount point', when logged in, it changed.
You can use the shell command 'mount' to check if you have the same way to use home directory.
So, i logged in and 'cd /', then do
```
cp -ar ${HOME}/.ssh /tmp/
sudo umount ${HOME}
mv /tmp/.ssh ${HOME}
```
There is may failed, because you need to check the ${HOME} if you have the right to write, if not, try sudo or add writable to ${HOME}.
After that, every thing being fine.
Please follow the below steps to avoid the error
http://umasarath52.blogspot.in/2013/09/solved-rsync-not-executing-via-cron.html
I resolved this issue by communicating with the administrators for my server. Here is what they told me:
For advanced security and performance, we use 1H (Hive) which
utilizes a chrooted environment for users. Libraries and binaries
should be copied to the chrooted environment to make them accessible.
They sent me a follow up email telling me that the "Relevent" packages have been installed. At that point, the problem was resolved. Unfortunately, I didn't get any additional information from them. The host was Arvixe, but I'm guessing that anyone using 1H (Hive) will encounter a similar problem. Hopefully this answer will be helpful.
Use the rrsync script together with a dedicated ssh key as follows:
REMOTE server
mkdir ~/bin
gunzip /usr/share/doc/rsync/scripts/rrsync.gz -c > ~/bin/rrsync
chmod +x ~/bin/rrsync
LOCAL computer
ssh-keygen -f ~/.ssh/id_remote_backup -C "Automated remote backup" #NO passphrase
scp ~/.ssh/id_remote_backup.pub devel#10.10.10.83:/home/devel/.ssh
REMOTE computer
cat id_remote_backup.pub >> authorized_keys
Prepend to the newly added line the following
command="$HOME/bin/rrsync -ro ~/backups/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding
So that the result looks like
command="$HOME/bin/rrsync -ro ~/backups/",no-agent-forwarding,no-port-forwarding,no-pty,no-user-rc,no-X11-forwarding ssh-rsa AAA...vp Automated remote backup
LOCAL
Put in your crontab the following script with x permission:
#!/bin/sh
echo ""
echo ""
echo "CRON:" `date`
set -xv
rsync -e "ssh -i $HOME/.ssh/id_remote_backup" -avzP devel#10.10.10.83:/ /home/user/servidor
Source: http://www.guyrutenberg.com/2014/01/14/restricting-ssh-access-to-rsync/
I did several steps to make it work.
Check your paths. For every command you'll use check which [command] and use that full path for the crontab
Open crontab as the user you want to run it with so it has access to that users ssh-key
Add (remember to user which) ssh-agent && [your ssh-command] so it can connect over ssh.
When authentication still fails at this point. Try to generate a passwordless ssh-key. This way you can skip the password prompting.
For debugging it is useful to add -vvv to the ssh command in rsync. It makes it clear what goes wrong.
Using the correct keyring solved the issue for me. Add the following line to your crontab:
SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
In total, your crontab (edited by calling crontab -e from your terminal) should now look as follows:
SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
0 4 * * * rsync -avz backups#odin.mydomain.net:/home/backups /home/myuser/odin
Background: It turns out that some Linux distributions use a keyring to protect your public-private key pair - so the key pair is password-protected without ever noticing you. Consequently, rsync is not able to open your ssh key for authentication.
Note that I also omitted the -e ssh; I think it is not necessary here.
Further Troubleshooting: rsync does not provide a lot of debugging output. What helped me identify the problem was to put a dummy scp command, which is much more verbose, in my crontab. A crontab entry for troubleshooting may look something like:
* * * * * scp -v backups#odin.mydomain.net:/home/backups/dummy.txt /home/myuser/odin/dummy.txt >> /home/myuser/odin/dummy.txt.log 2>&1
The above command will run every minute (great for developing) and it will copy a file /home/backups/dummy.txt to your local machine. All logs (stdout and stderr) are written to to /home/myuser/odin/dummy.txt.log. Inspect these logs to see where the error precisely comes from.
Reference: The troubleshooting explained above lead me to the solution: https://unix.stackexchange.com/a/332353/395749
Here's the context of the question:
In order for me to be able to print documents at work, I have to copy the file over to a different computer and then print from that computer. (Don't ask. It's complicated and there is not another viable solution.) Both of the computers are Linux and I work in bash. The way I currently do this is I scp the file over to the print computer and then ssh in and print from command line.
Here's what I would like to do:
In order to make my life a bit easier, I'd like to combine these two step into one. I could easily write a function that did both these steps, but I would have to provide my password twice. Is there any way to combine the steps so that I only provide my password once?
Before somebody suggests it, key-based ssh-logins are not an option. It has been specifically disabled by the Administrators for security reasons.
Solution:
What I ended up doing was a modification of the second solution Wrikken provided. Simply wrapping up his first suggestion in a function would have gotten the job done, but I liked the idea of being able to print multiple documents without having to type my password once per document. I have a rather long password and I'm a lazy typist :)
So, what I did was take a sequence of commands and wrap them up in a python script. I used python because I wanted to parameterize the script, and I find it easiest to do in python. I cheated and just ran bash commands from python through os.system. Python just handled parameterization and flow control. The logic was as follows:
if socket does not exist:
run bash command to create socket with timeout
copy file using the created socket
ssh command to print using socket
In addition to using a timeout, I also put have an option in my python script to manually close the socket should I wish to do so.
If anyone wants the code, just let me know and I'll either paste-bin it or put it on my git repo.
ssh user#host 'cat - > /tmp/file.ext; do_something_with /tmp/file.ext;rm /tmp/file.ext' < file.ext
Another option would be to just leave an ssh tunnel open:
In ~/.ssh/config:
Host *
ControlMaster auto
ControlPath ~/.ssh/sockets/ssh-socket-%r-%h-%p
.
$ ssh -f -N -l user host
(socket is now open)
Subsequent ssh/scp requests will reuse the already existing tunnel.
Here is bash script template, which follows #Wrikken's second method, but can be used as is - no need to edit user's SSH config file:
#!/bin/bash
TARGET_ADDRESS=$1 # the first script argument
HOST_PATH=$2 # the second script argument
TARGET_USER=root
TMP_DIR=$(mktemp -d)
SSH_CFG=$TMP_DIR/ssh-cfg
SSH_SOCKET=$TMP_DIR/ssh-socket
TARGET_PATH=/tmp/file
# Create a temporary SSH config file:
cat > "$SSH_CFG" <<ENDCFG
Host *
ControlMaster auto
ControlPath $SSH_SOCKET
ENDCFG
# Open a SSH tunnel:
ssh -F "$SSH_CFG" -f -N -l $TARGET_USER $TARGET_ADDRESS
# Upload the file:
scp -F "$SSH_CFG" "$HOST_PATH" $TARGET_USER#$TARGET_ADDRESS:"$TARGET_PATH"
# Run SSH commands:
ssh -F "$SSH_CFG" $TARGET_USER#$TARGET_ADDRESS -T <<ENDSSH
# Do something with $TARGET_PATH here
ENDSSH
# Close the SSH tunnel:
ssh -F "$SSH_CFG" -S "$SSH_SOCKET" -O exit "$TARGET_ADDRESS"