Read command in bash script not waiting for user input when piped to bash? - linux

Here is what I'm entering in Terminal:
curl --silent https://raw.githubusercontent.com/githubUser/repoName/master/installer.sh | bash
The WordPress installing bash script contains a "read password" command that is supposed to wait for users to input their MySQL password. But, for some reason, that doesn't happen when I run it with the "curl githubURL | bash" command. When I download the script via wget and run it via "sh installer.sh", it works fine.
What could be the cause of this? Any help is appreciated!

If you want to run a script on a remote server without saving it locally, you can try this.
#!/bin/bash
RunThis=$(lynx -dump http://127.0.0.1/example.sh)
if [ $? = 0 ] ; then
bash -c "$RunThis"
else
echo "There was a problem downloading the script"
exit 1
fi
In order to test it, I wrote an example.sh:
#!/bin/bash
# File /var/www/example.sh
echo "Example read:"
read line
echo "You typed: $line"
When I run Script.sh, the output looks like this.
$ ./Script.sh
Example read:
Hello World!
You typed: Hello World!
Unless you absolutely trust the remote scripts, I would avoid doing this without examining it before executing.

It wouldn't stop for read:
As when you are piping in a way you are forking a child which has been given input from parent shell.
You cannot give the values back to parent(modify parent's env) from child.
and through out this process you are always in parent process.

Related

ssh does not return even after execution

The following ssh command does not return to terminal. It hangs though the execution is completed. The execution hangs after echo hi command.
ssh user#testserver "echo hello;source .profile;source .bash_profile;/apps/myapp/deploytools/ciInstallAndRun.sh; echo hi"
Output
hello
<outoutfrom remote script"
hi
ciInstallAndRun.sh
echo 'starting'
cd /apps/myapp/current
./tctl kill
cd /apps/myapp
mv myapp_v1.0 "myapp_v1.0_`date '+%Y%m%d%H%M'`"
unzip -o /apps/myapp/myappdist-bin.zip
java -classpath .:/apps/myapp/deploytools/cleanup.jar se.telenor.project.cleanup.Cleanup /apps/myapp myapp_v1.0_ 3
cd /apps/myapp/myapp_v1.0
echo 'Done with deploy'
chmod -R 775 *
echo 'Done'
./tctl start test
Source OS: Redhat
Dest Os: Solaris 10 8/07
Any idea to fix this.
Any idea to fix this.
Your installation script has spawned a child process.
Add a ps -f or ptree $$ command before echo hi. You'll see a child process or multiple child processes spawned by your install script.
To stop the SSH command from hanging, you need to detach such child process(es) from your terminal's input/output. You can sedirect your script's output to a file - both stdout and stderr with > /some/output/file 2>&1, and also redirect its input with < /dev/null.
Or you can use the nohup command.
You haven't provided an MCVE, as others have noted, but this is likely the problem command in you install script, since your question implies that you see the expected output from your install script:
./tctl start test
You probably would do better to replace it with something like:
./tctl start test </dev/null >/some/log/file/path.log 2>&1

Launching a bash shell from a sudo-ed environment

Apologies for the confusing Question title. I am trying to launch an interactive bash shell from a shell script ( say shel2.sh) which has been launched by a parent script (shel1.sh) in a sudo-ed environment. ( I am creating a guided deployment
script for my software which needs to be installed as super-user , hence the sudo, but may need the user to access the shell. )
Here's shel1.sh
#!/bin/bash
set -x
sudo bash << EOF
echo $?
./shel2.sh
EOF
echo shel1 done
And here's shel2.sh
#!/bin/bash
set -x
bash --norc --verbose --noprofile -i
echo $?
echo done
I expected this to launch an interactive bash shell which waits for my input before returning to shel1.sh. This is what I see:
+ ./shel1.sh
+ sudo bash
0
+ bash --norc --verbose --noprofile -i
bash-4.3# exit
+ echo 0
0
+ echo done
done
+ echo shel1 done
shel1 done
The bash-4.3# calls an exit automatically and quits. Interestingly if I invoke the bash shell with -l (or --login) the automatic entry is logout !
Can someone explain what is happening here ?
When you use a here document, you are tying up the shell's -- and its spawned child processes' -- standard input to the here document input.
You can avoid using a here document in many situations. For example, replace the here document with a single-quoted string.
#!/bin/bash
set -x
sudo bash -c '
# Aside: How is this actually useful?
echo $?
# Spawned script inherits the stdin of "sudo bash"
./shel2.sh'
echo shel1 done
Without more details, it's hard to see where exactly you want to go with this, but most modern Linux platforms have package managers which allow all kinds of hooks for installation, so that you would typically not need to do this sort of thing. Have you looked into that?

bash: what to do when stdout does not exist

In a very simplified scenario, I have a script that looks like this:
mv test _test
sleep 10
echo $1
mv _test test
and if I execute it with:
ssh localhost "test.sh foo"
the test file will have an underscore in the name as long as the script is running, and when the script is finished, it will send foo back. The script SHOULD keep running, even if you terminate the ssh command by pressing ctrl+c or if you lose connection the the server, but it doesn't (the file is not renamed back to "test"). So, I tried the following:
nohup ssh localhost "test.sh foo"
and it makes ssh immune to ctrl+c but flaky connection to the server still causes trouble. After some debugging, it turns out that the script WILL actually reach the end IF THERE IS NO ECHO IN IT. And when you think about it, it makes sense - when the connection is dropped, there is no more stdout (ssh socket) to echo to, so it will fail, silently.
I can, of course, echo to a file and then get the file, but I would prefer something smarter, along the lines of test tty && echo $1 (but tty invoked like this always returns false). Any suggestions are greatly appreciated.
The following command does what you want:
ssh -t user#host 'nohup ~/test.sh foo > nohup.out 2>&1 & p1=$!; tail -f ~/nohup.out & wait $p1'
... test.sh is located in the users home directory
Explanation:
1.) "ssh -t user#host " ... pretty clear ... starts remote session
2.) "nohup ~/test.sh foo > nohup.out 2>&1" ... starts the test.sh script with nohup in background
3.) "p1=$!;" ... stores the child pid of the previous command in p1
4.) "tail -f ~/nohup.out &" ... tail nohup.out in background to see the output of test.sh
5.) "wait $p1" ... waits for proccess test.sh (which pid is stored in p1) to finish
The above command works even if you interrupt it with ctrl+c.
you can use ...
ssh -t localhost "test.sh foo"
... to force a tty allocation
As st0ne suggested, tail fails, but does not cause the script to terminate, as opposed to cat and echo. So, there is no need for nohup, redirecting stdout to a temporary file, etc. just plain and simple:
mv test _test
sleep 10
echo $1 | tail
mv _test test
and execute it with:
ssh localhost "test.sh foo"

Keep a script running through ssh after logout

This is the first question that I post here. I tried to do a throughout search, but if I haven't (and the answer is obvious somewhere else), please just let me know.
I have a script that runs a program for me, here it is:
csv_file=../data/teste_nohup.csv
trace_file=../data/gnp.trace
declare -i n=100
declare -i p=1
declare -i counter=0
while [ $counter -lt 3 ];
do
n=100
while true
do
nice -19 sage gnptest.py ${n} ${p} | tee -a ${csv_file}
notify-send "finished test gnp ${n} ${p}"
done
done
So, what I'm trying to do is run the gnptest.py program a few times, and have the result be written to the csv_file.
The problem is, that depending on the input, the program may take a long time to complete. So I'd like to connect to the server over ssh, start the program, close the terminal, and check the output file from time to time.
I've tried nohup and disown. Nohup creates a huge nohup.out file, full with errors that I don't get while normally running the script (it complains about using the -lt operand, for example). But the biggest problem that I'm facing is that no command (nohup ou disown -h) is executing the program and sending the output to the file that I've specified in the csv_file variable, which is being done using the tee command. Also, none of them seem to continue running after I logout...
Any help will be much appreciated.
Thanks in advance!!
i hv just joined so cannt add comment
Please try by using redirection instead of tee in script
And to get rid of Nohup.out use following to run script
nohup script.sh > /dev/null 2>&1 &
If above produces error use
nohup script.sh > /dev/null 2>&1 </dev/null &
Hope this will help.

Redirecting Output of Bash Child Scripts

I have a basic script that outputs various status messages. e.g.
~$ ./myscript.sh
0 of 100
1 of 100
2 of 100
...
I wanted to wrap this in a parent script, in order to run a sequence of child-scripts and send an email upon overall completion, e.g. topscript.sh
#!/bin/bash
START=$(date +%s)
/usr/local/bin/myscript.sh
/usr/local/bin/otherscript.sh
/usr/local/bin/anotherscript.sh
RET=$?
END=$(date +%s)
echo -e "Subject:Task Complete\nBegan on $START and finished at $END and exited with status $RET.\n" | sendmail -v group#mydomain.com
I'm running this like:
~$ topscript.sh >/var/log/topscript.log 2>&1
However, when I run tail -f /var/log/topscript.log to inspect the log I see nothing, even though running top shows myscript.sh is currently being executed, and therefore, presumably outputting status messages.
Why isn't the stdout/stderr from the child scripts being captured in the parent's log? How do I fix this?
EDIT: I'm also running these on a remote machine, connected via ssh using pseudo-tty allocation, e.g. ssh -t user#host. Could the pseudo-tty be interfering?
I just tried your the following: I have three files t1.sh, t2.sh, and t3.sh all with the following content:
#!/bin/bash
for((i=0;i<10;i++)) ; do
echo $i of 9
sleep 1
done
And a script called myscript.sh with the following content:
#!/bin/bash
./t1.sh
./t2.sh
./t3.sh
echo "All Done"
When I run ./myscript.sh > topscript.log 2>&1 and then in another terminal run tail -f topscript.log I see the lines being output just fine in the log file.
Perhaps the things being run in your subscripts use a large output buffer? I know when I've run python scripts before, it has a pretty big output buffer so you don't see any output for a while. Do you actually see the entire output in the email that gets sent out at the end of topscript.sh? Is it just that while the processes run you're not seeing the output?
try
unbuffer topscript.sh >/var/log/topscript.log 2>&1
Note that unbuffer is not always available as a std binary in old-style Unix platforms and may require a search and installation for a package to support it.
I hope this helps.

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