I have the following script in bash:
ssh user#1.1.1.1 "echo 'start'
mkdir -p /home/user/out
cp /tmp/big_file /home/user/out
echo 'syncing flash'
sync
while [[ $(cat /proc/meminfo | grep Dirty | awk '{print $2}') -ne 0 ]] ; do
echo \"$(cat /proc/meminfo)\"
sleep 1
sync
done
echo 'done'"
I have my host PC and a target PC which I am copying to. Before I run this script I have already scp'd a big file into /tmp on the target.
When I run this script it copies the file /tmp/big ok, but when it enters the loop to sync the flash and I wait for meminfo Dirty to get to zero what I see is always Dirty: 74224 kB repeated in the loop.
However in a different ssh session logged in to the target I have it running:
watch -n1 "cat /proc/meminfo | grep Drity"
And I see this count down from ~74000kb to 0kB.
The difference is that the ssh session doing the watch is logged in as root and the ssh is logged in a user.
So I did the same test with the ssh shell logged in as user and I saw always 0kb in Drity...
Does this imply that the user can't read meminfo relating to the whole system? - how can I tell when the flash has sync'd as a non-root user?
Since the argument to ssh is in double quotes, variables and command substitutions are expanded locally on the client before sending the command, they're not done on the remote machine. Since they're substituted on the client, you'll obviously get the same result each time through the loop (because the client isn't looping).
You should either escape the $ characters so they're sent to the server, or put the command inside single quotes (but the latter makes it difficult to include single quotes in the command).
ssh user#1.1.1.1 "echo 'start'
mkdir -p /home/user/out
cp /tmp/big_file /home/user/out
echo 'syncing flash'
sync
while [[ \$(awk '/Dirty/ {print \$2}' /proc/meminfo) -ne 0 ]] ; do
cat /proc/meminfo
sleep 1
sync
done
echo 'done'"
There's also no need for cat /proc/meminfo and grep Dirty in the command substitution. awk can do pattern matching and take a filename argument.
Related
I was watching the infamous beginners' network pentesting video of Heath Adams and was attempting to make nmap staging script.
Can someone explain why I am getting this irksome permission denied error where I defined the ports variable even though my script has been running without a hitch up until this point?
Here is the staging script I am attempting:
#!/bin/bash
#creating a temp directory to store the output of initial scan
mkdir tempStager
#scannig with given flags and storing the results
echo beginning nmap scan
nmap $* > tempStager/scan.txt
echo basic nmap scan complete
#retrieving open ports
cat tempStager/scan.txt |grep tcp |cut -d " " -f 1| tr -d "/tcp" > tempStager/ports.txt
sleep 2
ports=cat tempStager/ports.txt| awk '{printf "%s,",$0}' tempStager/ports.txt
ip=echo $* | awk 'NF{ print $NF }'
#scanning with -A
#echo ""
#echo starting nmap scan with -A
#nmap -A -p$ports $ip
#removing temp directory
#rm -r tempStager```
ports=cat tempStager/ports.txt| awk '{printf "%s,",$0}' tempStager/ports.txt
assigns the variable the value "cat" and then tries to execute tempStager/ports.txt as an executable. But the file is not an executable (it doesn't have the x bit set, so it cannot be executed.
ports only exists for the runtime of the (would-be) program, it is not available after the program has terminated (which the program does immediately, because your shell fails to run it).
You are also specifying stdin and a file to awk.
If you want to assign the output of awk to a variable, you must use command substitution:
ports="$(awk '{printf "%s,",$0}' tempStager/ports.txt)"
I'm getting the following mail every time I execute a specific cronjob. The called script runs fine when I'm calling it directly and even from cron. So the message I get is not an actual error, since the script does exactly what it is supposed to do.
Here is the cron.d entry:
* * * * * root /bin/bash -l -c "/opt/get.sh > /tmp/file"
and the get.sh script itself:
#!/bin/sh
#group and url
groups="foo"
url="https://somehost.test/get.php?groups=${groups}"
# encryption
pass='bar'
method='aes-256-xts'
pass=$(echo -n $pass | xxd -ps | sed 's/[[:xdigit:]]\{2\}/&/g')
encrypted=$(wget -qO- ${url})
decoded=$(echo -n $encrypted | awk -F '#' '{print $1}')
iv=$(echo $encrypted | awk -F '#' '{print $2}' |base64 --decode | xxd -ps | sed 's/[[:xdigit:]]\{2\}/&/g')
# base64 decode input and save to file
output=$(echo -n $decoded | base64 --decode | openssl enc -${method} -d -nosalt -nopad -K ${pass} -iv ${iv})
if [ ! -z "${output}" ]; then
echo "${output}"
else
echo "Error while getting information"
fi
When I'm not using the bash -l syntax the script hangs during the wget process. So my guess would be that it has something to do with wget and putting the output to stdout. But I have no idea how to fix it.
You actually have two questions here.
Why it prints stdin: is not a tty?
This warning message is printed by bash -l. The -l (--login) options asks bash to start the login shell, e.g. the one which is usually started when you enter your password. In this case bash expects its stdin to be a real terminal (e.g. the isatty(0) call should return 1), and it's not true if it is run by cron—hence this warning.
Another easy way to reproduce this warning, and the very common one, is to run this command via ssh:
$ ssh user#example.com 'bash -l -c "echo test"'
Password:
stdin: is not a tty
test
It happens because ssh does not allocate a terminal when called with a command as a parameter (one should use -t option for ssh to force the terminal allocation in this case).
Why it did not work without -l?
As correctly stated by #Cyrus in the comments, the list of files which bash loads on start depends on the type of the session. E.g. for login shells it will load /etc/profile, ~/.bash_profile, ~/.bash_login, and ~/.profile (see INVOCATION in manual bash(1)), while for non-login shells it will only load ~/.bashrc. It seems you defined your http_proxy variable only in one of the files loaded for login shells, but not in ~/.bashrc. You moved it to ~/.wgetrc and it's correct, but you could also define it in ~/.bashrc and it would have worked.
in your .profile, change
mesg n
to
if `tty -s`; then
mesg n
fi
I ended up putting the proxy configuration in the wgetrc. There is now no need to execute the script on a login shell anymore.
This is not a real answer to the actual problem, but it solved mine.
If you run into this problem check if you are getting all the environment variables set as you expect. Thanks to Cyrus for putting me to the right direction.
I'm using scp command to copy file from one Linux host to another.
I run scp commend on host1 and copy file from host1 to host2. File is quite big and it takes for some time to copy it.
On host2 file appears immediately as soon as copying was started. I can do everything with this file even if copying is still in progress.
Is there any reliable way to find out if copying was finished or not on host2?
Off the top of my head, you could do something like:
touch tinyfile
scp bigfile tinyfile user#host:
Then when tinyfile appears you know that the transfer of bigfile is complete.
As pointed out in the comments, this assumes that scp will copy the files one by one, in the order specified. If you don't trust it, you could do them one by one explicitly:
scp bigfile user#host:
scp tinyfile user#host:
The disadvantage of this approach is that you would potentially have to authenticate twice. If this were an issue you could use something like ssh-agent.
On sending side (host1) use script like this:
#!/bin/bash
echo 'starting transfer'
scp FILE USER#DST_SERVER:DST_PATH
OUT=$?
if [ $OUT = 0 ]; then
echo 'transfer successful'
touch successful
scp successful USER#DST_SERVER:DST_PATH
else
echo 'transfer faild'
fi
On receiving side (host2) make script like this:
#!/bin/bash
SLEEP_TIME=30
MAX_CNT=10
CNT=0
while [[ ! -e successful && $CNT < $MAX_CNT ]]; do
((CNT++))
sleep($SLEEP_TIME);
done;
if [[ -e successful ]]; then
echo 'successful'
rm successful
# do somethning with FILE
fi
With CNT and MAX_CNT you disable endless loop (in case file successful isn't transferred).
Product MAX_CNT and SLEEP_TIME should be equal or greater expected transfer time. In my example expected transfer time is less than 300 seconds.
A checksum (md5sum, sha256sum ,sha512sum) of the local and remote files would tell you if they're identical.
For the situation where you don't have SSH access to the remote system - like an FTP server - you can download the file after it's uploaded and compare the checksums. I do this for files I send from production scripts at work. Below is a snippet from the script in which I do this.
MD5SRC=$(md5sum $LOCALFILE | cut -c 1-32)
MD5TESTFILE=$(mktemp -p /ramdisk)
curl \
-o $MD5TESTFILE \
-sS \
-u $FTPUSER:$FTPPASS \
ftp://$FTPHOST/$REMOTEFILE
MD5DST=$(md5sum $MD5TESTFILE | cut -c 1-32)
if [ "$MD5SRC" == "$MD5DST" ]
then
echo "+Local and Remote files match!"
else
echo "-Local and Remote files don't match"
fi
if you use inotify-tools,
then the solution will looks like this:
while ! inotifywait -e close $(dirname ${bigfile_fullname}) 2>/dev/null | \
grep -Eo "CLOSE $(basename ${bigfile_fullname})$">/dev/null
do true
done
echo "File ${bigfile_fullname} closed"
After some investigation, and discussion of the problem on other forums I have found one more solution. Maybe it can help somebody.
There is a command "lsof". It lists open files. During copying the file will be opened, so the command
lsof | grep filename
will return non empty result.
So you might want to make a while loop to wait until lsof returns nothing and proceed with your task.
Example:
# provide your file name here
f=<nameOfYourFile>
lsofresult=`lsof | grep $f | wc -l`
while [ $lsofresult != 0 ]; do
echo still copying file $f...
sleep 5
lsofresult=`lsof | grep $f | wc -l`
done; echo copying file $f is finished: `ls $f`
For the duplicate question, How to check if file has been scp 100% to the remote location , which was for an expect script, to know if a file is transferred completely, we can add expect 100% .. .. i.e something like this ...
expect -c "
set timeout 1
spawn scp user#$REMOTE_IP:/tmp/my.file user#$HOST_IP:/home/.
expect yes/no { send yes\r ; exp_continue }
expect password: { send $SCP_PASSWORD\r }
expect 100%
sleep 1
exit
"
if [ -f "/home/my.file" ]; then
echo "Success"
fi
If avoiding a second SSH handshake is important, you can use something like the following:
ssh host cat \> bigfile \&\& touch complete < bigfile
Then wait for the "complete" file to get created on the remote end.
There are other threads with this same topic but my issue is unique. I am running a bash script that has a function that sshes to a remote server and runs a sudo command on the remote server. I'm using the ssh -t option to avoid the requiretty issue. The offending line of code works fine as long as it's NOT being called from within the while loop. The while loop basically reads from a csv file on the local server and calls the checkAuthType function:
while read inputline
do
ARRAY=(`echo $inputline | tr ',' ' '`)
HOSTNAME=${ARRAY[0]}
OS_TYPE=${ARRAY[1]}
checkAuthType $HOSTNAME $OS_TYPE
<more irrelevant code>
done < configfile.csv
This is the function that sits at the top of the script (outside of any while loops):
function checkAuthType()
{
if [ $2 == linux ]; then
LINE=`ssh -t $1 'sudo grep "PasswordAuthentication" /etc/ssh/sshd_config | grep -v "yes\|Yes\|#"'`
fi
if [ $2 == unix ]; then
LINE=`ssh -n $1 'grep "PasswordAuthentication" /usr/local/etc/sshd_config | grep -v "yes\|Yes\|#"'`
fi
<more irrelevant code>
}
So, the offending line is the line that has the sudo command within the function. I can change the command to something simple like "sudo ls -l" and I will still get the "stdin is not a terminal" error. I've also tried "ssh -t -t" but to no avail. But if I call the checkAuthType function from outside of the while loop, it works fine. What is it about the while loop that changes the terminal and how do I fix it? Thank you one thousand times in advance.
Another option to try to get around the problem would be to redirect the file to a different file descriptor and force read to read from it instead.
while read inputline <&3
do
ARRAY=(`echo $inputline | tr ',' ' '`)
HOSTNAME=${ARRAY[0]}
OS_TYPE=${ARRAY[1]}
checkAuthType $HOSTNAME $OS_TYPE
<more irrelevant code>
done 3< configfile.csv
I am guessing you are testing with linux. You should try add the -n flag to your (linux) ssh command to avoid having ssh read from stdin - as it normally reads from stdin the while loop is feeding it your csv.
UPDATE
You should (usually) use the -n flag when scripting with SSH, and the flag is typically needed for 'expected behavior' when using a while read-loop. It does not seem to be the main issue here, though.
There are probably other solutions to this, but you could try adding another -t flag to force pseudo-tty allocation when stdin is not a terminal:
ssh -n -t -t
BroSlow's approach with a different file descriptor seems to work! Since the read command reads from fd 3 and not stdin,
ssh and hence sudo still have or get a tty/pty as stdin.
# simple test case
while read line <&3; do
sudo -k
echo "$line"
ssh -t localhost 'sudo ls -ld /'
done 3<&- 3< <(echo 1; sleep 3; echo 2; sleep 3)
I'm trying to have a lightweight memory profiler for the matlab jobs that are run on my machine. There is either one or zero matlab job instance, but its process id changes frequently (since it is actually called by another script).
So here is the bash script that I put together to log memory usage:
#!/bin/bash
pid=`ps aux | grep '[M]ATLAB' | awk '{print $2}'`
if [[ -n $pid ]]
then
\grep VmSize /proc/$pid/status
else
echo "no pid"
fi
when I run this script in bash like this:
./script.sh
it works fine, giving me the following result:
VmSize: 1289004 kB
which is exactly what I want.
Now, I want to run this periodically. So I run it with watch, like this:
watch ./script.sh
But in this case I only receive:
no pid
Please note that I know the matlab job is still running, because I can see it with the same pid on top, and besides, I know each matlab job take several hours to finish.
I'm pretty sure that something is wrong with the quotes I have when setting pid. I just can't figure out how to fix it. Anyone knows what I'm doing wrong?
PS.
In the man page of watch, it says that commands are executed by sh -c. I did run my script like sh -c ./script and it works just fine, but watch doesn't.
Why don't you use a loop with sleep command instead?
For example:
#!/bin/bash
pid=`ps aux | grep '[M]ATLAB' | awk '{print $2}'`
while [ "1" ]
do
if [[ -n $pid ]]
then
\grep VmSize /proc/$pid/status
else
echo "no pid"
fi
sleep 10
done
Here the script sleeps(waits) for 10 seconds. You can set the interval you need changing the sleep command. For example to make the script sleep for an hour use sleep 1h.
To exit the script press Ctrl - C
This
pid=`ps aux | grep '[M]ATLAB' | awk '{print $2}'`
could be changed to:
pid=$(pidof MATLAB)
I have no idea why it's not working in watch but you could use a cron job and make the script log to a file like so:
#!/bin/bash
pid=$(pidof MATLAB) # Just to follow previously given advice :)
if [[ -n $pid ]]
then
echo "$(date): $(\grep VmSize /proc/$pid/status)" >> logfile
else
echo "$(date): no pid" >> logfile
fi
You'd of course have to create logfile with touch.
You might try just running ps command in watch. I have had issues in the past with watch chopping lines and such when they get too long.
It can be fixed by making the terminal you are running the command from wider or changing the column like this (may need to adjust the 160 to your liking):
export COLUMNS=160;