I am writing a bash script to check on multiple servers if Tomcat 5 is installed. When running the script, even if the find command stored in the variable command returns nothing, the tomcat variable is still set to '1' in the if statement.
I know there must be something wrong with my if statement but I'm not sure what. Below is the function that runs the command on the remote server
function search() {
local login=$1
local server_fqdn=$2
local command="sudo find / -name \"tomcat-5*\""
ssh -oBatchMode=yes -o ConnectTimeout=6 $login#$server_fqdn "$command"
if [ "$?" = 0 ];
then
echo "Tomcat found"
tomcat=1
else
echo "No tomcat here!"
fi
}
How can I get the function to enter the 'else' condition if command returns nothing?
The immediate problem is: find returns 0 when not failing regardless of whether it found anything or not, you may be assuming behavior similar to grep, but that's not the case. You could capture its output res=$(find ...) and test if it is not empty (test -n), but...
But honestly, this is a rather odd way to detect present of installed SW which is quite error prone. To say the least, imagine you've left a file with notes for later: my_tomcat-5_hints.
Perhaps ask your packaging manager if being used on the host... or at least check for existence of specific file(s)/dir(s)?
You should generally not need to be superuser to tell either and if you do, it's a little odd to ssh in as one user just to sudo in the next step if it really was needed.
Related
I have a .conf file that I am calling in my main script, which contains a case statement.
In this file, I have a series of ssh commands that I am combining into a single variable/array/function (I've tried multiple methods) to be executed when the condition is met in my case statement. For context, this is a script to auto-shutdown clients.
~/variables.conf
#!/bin/sh
CLIENT_1="ssh admin#1.1.1.1 shutdown -r now"
CLIENT_2="ssh admin#1.1.1.2 shutdown -r now"
CLIENT_ALL() { $CLIENT_1 ; $CLIENT_2 ; }
#also tried with similar results
#CLIENT_ALL="$CLIENT_1; $CLIENT_2"
#CLIENT_ALL=($CLIENT_1 $CLIENT_2)
To make sure this portion of code is working and the variables are passing, I run a test.sh and execute from CLI.
~/variables.test.sh
#!/bin/sh
. ~/variables.conf
CLIENT_ALL
Great, everything works. My two clients restart successfully - ssh keys stored so no prompt to enter password.
But when this is called from my case statement, things go wrong:
~/script.sh
#!/bin/sh
. ~/variables.conf
case $1 in
trigger1)
logger <message> #this is working fine
printf <message> | msmtp <email> #this is working fine
CLIENT_ALL
;;
*)
logger "Unrecognized command: $1"
;;
esac
What happens when this triggers: it logs, it sends an email but only the first client gets the ssh command to reboot. It passes the first variable $CLIENT_1 and then stops. I've tried a variety of ways to define and package the ssh commands, as well as a variety of ways to call them in the case statement, but always with the same results. I am certain that there is something about case statement rules/logic that I am overlooking that will explain this behavior and a correct way to make this work.
For my use-case, I need to use a case statement. My goal is to have a single command in the case statement so that the main script doesn't have to be modified - only the .conf needs to be updated if clients are added/removed.
Any help would be greatly appreciated.
Context
While setting up a basic unit testing system, I ran into an odd issue.
My goal was to make sure all individual test scripts:
were run with set -e to detect errors, without needing to explicitly set this in each file;
knew right away about the functions to be tested (stored in another file) without needing to explicitly source those in each test file.
Observations
Let this be a dummy test file called to-be-sourced.sh. We want to be able to know if a command in it fails:
# Failing command!
false
# Last command is OK:
true
And here is a dummy test runner, which must run the test file:
#! /usr/bin/env bash
if (
set -e
. to-be-sourced.sh
)
then
echo 'Via set: =0'
else
echo 'Via set: ≠0'
fi
This yields Via set: =0, meaning that the runner is happy. But it should not!
My hypothesis was:
set -e is not propagated within . sourcing, and as explained in the help for . and source, the exit status is the one of the last command.
But then I came up with a workaround that works, but also relies on .:
if bash -ec '. "$0"' to-be-sourced.sh
then
echo 'Via bash: =0'
else
echo 'Via bash: ≠0'
fi
This yields ≠0 whenever a command in the test file fails, regardless of whether that command was the last one of the test file. As a bonus, I can toss any number of . a/library/file.sh within the -c command, so each test file can use all of my functions out of the box. I should therefore be happy, but:
Why does this work, considering that the -c command also relies on . to load the test file (and I thought bash’s -e was equivalent to set’s -e)?
I also thought about using bash’s --init-file, but it appeared to be skipped when a script is passed as a parameter. And anyway my question is not so much about what I was trying to achieve, but rather about the observed difference of behavior.
Edit
Sounds like if is tempering with the way set -e is handled.
This halts execution, indicating failure:
. to-be-sourced.sh
… while this goes into the then (not the else), indicating success:
if . to-be-sourced.sh
then
echo =0
else
echo ≠0
fi
(This may not be precisely correct, but I think it captures what happens.)
In your first example, set -e sets the option in a command that is lexically in the scope of an if statement, and so even though it is set, it is ignored. (You can confirm it is set by running echo $- inside to-be-sourced.sh. Note, too, that . itself has a 0 exit status, which you can confirm by replacing true with an echo statement; it's not that it fails but the failure is ignored.)
In your second example, -e sets the errexit option in a new process, which knows nothing about the if statement and therefore it is not ignored.
I need help with some scripts I'm writing.
Scenario:
Script A is executed by a scheduling process. This script takes the arguments passed to it, parses them in some way and runs script B feeding it with those arguments;
Script B does sudo -u user ssh user#REMOTEMACHINE, runs some commands (in the remote machine) and finally runs script C (also in the remote machine). I am passing those commands using a HERE DOCUMENT. Also, I'm passing the previous arguments to this script too.
This "flow" runs correctly and the job completes successfully.
My problems are:
Since this "flow" is ran by a scheduling process, I need to tell it if the job completed successfully or not. I'm doing this via exit codes, so what I want is to have a chain of exit codes, returning back from the last script to the first, in case of errors. I'm not able to perform this, because exit codes works correctly for the single scripts (I tried executing them singularly and look for the exit codes), but they are not sended back to the parent script. In my opinion, the problem is that ssh is getting the exit code from the child script, which in fact ended successfully, because there was no error executing it: it's the command inside of it that gone wrong.
While the process works correctly, I still get this line:
ssh: Could not resolve hostname : Name or service not known
But actually the script completes successfully.
I hope you understand what I wrote, I can eventually post my scripts here.
Thanks
O.
EDIT:
This are the scripts. There could be some problem with variable names because I renamed it quikly to upload the files.
Since I can't upload 3 files because of my low reputation, I merged them in a single file
SCRIPT FILE
I managed to solve the problem.
I followed olivier's advice and used the escape char to make the variable expanded by the remote machine.
Also I implemented different exit codes based on where the error occured.
At last, I modified the first script as follows, after launching sudo -u for the second script:
EXITCODEOFTHESECONDSCRIPT=$?
if [ $EXITCODEOFTHESECONDSCRIPT = 0 ]
then
echo ""
echo "Export job took $SECONDS seconds."
echo ""
exit 0
else
exit $EXITCODEOFTHESECONDSCRIPT
fi
This way I am able to exit the main script MAINTAINING the exit code provided from the second script.
In fact, I found that the problem was that the process worked well, even in case of errors, but the fact that I was giving more commands after the second script fail (the echo command was enough) provided other exit codes that overwrited the one I wanted.
Thanks to all !
I've only been writing actual .sh scripts since sometime this morning, and I'm a bit stuck. I'm trying to write a script to check to see if a process is running, and to start it if it isn't. (I plan to run this script once every 10 to 15 minutes with cron.)
Here's what I have so far:
#!/bin/bash
APPCHK=$(ps aux | grep -c "/usr/bin/rsync -rvz -e ssh /home/e-smith/files/ibays/drive-i/files/Warehouse\ Pics/organized_pics imgserv#192.168.0.140:~/webapps/pavlick_container/public/images
")
RUNSYNC=$(rsync -rvz -e ssh /home/e-smith/files/ibays/drive-i/files/Warehouse\ Pics/organized_pics imgserv#192.168.0.140:~/webapps/pavlick_container/public/images)
if [ $APPCHK < '2' ];
then
$RUNSYNC
fi
exit
Here's the error that I'm getting:
$ ./image_sync.sh
rsync: mkdir "/home/i/webapps/pavlick_container/public/images" failed: No such file or directory (2)
rsync error: error in file IO (code 11) at main.c(595) [Receiver=3.0.7]
rsync: connection unexpectedly closed (9 bytes received so far) [sender]
rsync error: error in rsync protocol data stream (code 12) at io.c(601) [sender=3.0.7]
./image_sync.sh: line 8: 2: No such file or directory
TRTWF is that
rsync -rvz -e ssh /home/e-smith/files/ibays/drive-i/files/Warehouse\ Pics/organized_pics imgserv#192.168.0.140:~/webapps/pavlick_container/public/images
runs just fine from a terminal window.
What am I doing wrong?
Your grep call is wrong on two counts. The pattern shouldn't include a newline. To look for an exact string, use grep -F 'substring' or grep -xF 'exact whole line'.
Finding if a process is running with ps | grep is highly brittle. On most unices (at least Solaris, Linux and *BSD), use pgrep: pgrep -f 'PATTERN' returns true if there's a running process whose command line matches PATTERN.
Every program returns a status code, either 0 to indicate success or a number between 1 and 255 to indicate failure. In the shell, any command is a valid boolean expression; the status code 0 is treated as true and anything else as false.
$(…) means run the command inside the parentheses and capture its output. So rsync is executed as soon as the shell hits the definition of the RUNSYNC variable. To store a block of shell code, use a function (example below, although you don't actually need a function here, you could just write the code directly).
Your test [ $APPCHK < 2 ] should be [ $APPCHK -lt 2 ]: < means input redirection. (In bash, you can also write [[ foo < bar ]], but that's string comparison, not numeric comparison.)
~/ at the beginning of the remote rsync path is optional. Also, -e ssh is the default unless your version of rsync is really old.
exit at the end of the script is useless, the script will exit anyway.
Here's a script taking the above into account:
#!/bin/bash
run_rsync () {
rsync -rvz '/home/e-smith/files/ibays/drive-i/files/Warehouse Pics/organized_pics' \
imgserv#192.168.0.140:webapps/pavlick_container/public/images
}
process_pattern='/usr/bin/rsync -rvz /home/e-smith/files/ibays/drive-i/files/Warehouse Pics/organized_pics imgserv#192\.168\.0\.140:webapps/pavlick_container/public/images'
if pgrep -xF "$process_pattern"; then
run_rsync
fi
Looks like with your rsync command that some directory along this path is wrong: ~/webapps/pavlick_container/public/images
Have you checked on the server 192.168.0.140 in imgserv's home directory to see if "pavlick_container/public" exists? That's my guess.
You have a number of problems. First you are running the commands instead of putting the commands in variables. There is also a much easier way.
RUNSYNC="rsync -rvz -e ssh /home/e-smith/files/ibays/drive-i/files/Warehouse\ Pics/organized_pics imgserv#192.168.0.140:~/webapps/pavlick_container/public/images"
if ! pgrep -f "rsync.*organized_pics"; then $RUNSYNC; fi
First of all, the way of checking if the program is running is mostly wrong. This may or may not work. You should rely on some special file you create when your script starts, that it is deleted when your script ends. This will tell you if the script is running, just checking if this file exists.
Then, try to either put a \ before the ~ or to remove the ~/ completely. If cron is run as other user, the tilde will be substituted in the client for the user directory. It works for the command line because maybe the home directory of your user in both machines match, but not in the user the cron is running. A guess at this point, but again, try to remove the ~/ and see if it works.
If your real code is missing a closing dlb-quote on the grep target, you're going to get weird results from the get-go.
Also, ps aux will not list a complete command line result like you show (at least on all the the pss I have used).
You need to make it ps auxwww. Often you will see people add | grep -v grep | (you'll see why at some point). This can be reduced to changing your static search target slightly like "/usr/bin/rsync" to "/usr/bin/[r]sync ".
Other users are also helping with their comments. Using a flag file as #DiegoSevilla mentions is marginally deprecated. use a mkdir /tmp/MyWatcher_flagDir for your flag. Directory creation is an atomic activity (where as file creations are not), and this will eliminate any errors you might encounter from having 2 copies of you monitor try to make a flag file at the same time. Only one process will succeed in making or removing a flag dir.
I hope this helps.
Not having much luck Googling this question and I thought about posting it on SF, but it actually seems like a development question. If not, please feel free to migrate.
So, I have a script that runs via cron every morning at about 3 am. I also run the same scripts manually sometimes. The problem is that every time I run my script manually and it fails, it sends me an e-mail; even though I can look at the output and view the error in the console.
Is there a way for the bash script to tell that it's being run through cron (perhaps by using whoami) and only send the e-mail if so? I'd love to stop receiving emails when I'm doing my testing...
you can try "tty" to see if it's run by a terminal or not. that won't tell you that it's specifically run by cron, but you can tell if its "not a user as a prompt".
you can also get your parent-pid and follow it up the tree to look for cron, though that's a little heavy-handed.
I had a similar issue. I solved it with checking if stdout was a TTY. This is a check to see if you script runs in interactive mode:
if [ -t 1 ] ; then
echo "interacive mode";
else
#send mail
fi
I got this from: How to detect if my shell script is running through a pipe?
The -t test return true if file descriptor is open and refers to a terminal. '1' is stdout.
Here's two different options for you:
Take the emailing out of your script/program and let cron handle it. If you set the MAILTO variable in your crontab, cron will send anything printed out to that email address. eg:
MAILTO=youremail#example.com
# run five minutes after midnight, every day
5 0 * * * $HOME/bin/daily.job
Set an environment variable in your crontab that is used to determine if running under cron. eg:
THIS_IS_CRON=1
# run five minutes after midnight, every day
5 0 * * * $HOME/bin/daily.job
and in your script something like
if [ -n "$THIS_IS_CRON" ]; then echo "I'm running in cron"; else echo "I'm not running in cron"; fi
Why not have a command line argument that is -t for testing or -c for cron.
Or better yet:
-e=email#address.com
If it's not specified, don't send an email.
I know the question is old, but I just came across the same problem. This was my solution:
CRON=$(pstree -s $$ | grep -q cron && echo true || echo false)
then test with
if $CRON
then
echo "Being run by cron"
else
echo "Not being run by cron"
fi
same idea as the one that #eruciform mentioned - follows your PID up the process tree checking for cron.
Note: This solution only works specifically for cron, unlike some of the other solutions, which work anytime the script is being run non-interactively.
What works for me is to check $TERM. Under cron it's "dumb" but under a shell it's something else. Use the set command in your terminal, then in a cron-script and check it out
if [ "dumb" == "$TERM" ]
then
echo "cron"
else
echo "term"
fi
I'd like to suggest a new answer to this highly-voted question. This works only on systemd systems with loginctl (e.g. Ubuntu 14.10+, RHEL/CentOS 7+) but is able to give a much more authoritative answer than previously presented solutions.
service=$(loginctl --property=Service show-session $(</proc/self/sessionid))
if [[ ${service#*=} == 'crond' ]]; then
echo "running in cron"
fi
To summarize: when used with systemd, crond (like sshd and others) creates a new session when it starts a job for a user. This session has an ID that is unique for the entire uptime of the machine. Each session has some properties, one of which is the name of the service that started it. loginctl can tell us the value of this property, which will be "crond" if and only if the session was actually started by crond.
Advantages over using environment variables:
No need to modify cron entries to add special invocations or environment variables
No possibility of an intermediate process modifying environment variables to create a false positive or false negative
Advantages over testing for tty:
No false positives in pipelines, startup scripts, etc
Advantages over checking the process tree:
No false positives from processes that also have crond in their name
No false negatives if the script is disowned
Many of the commands used in prior posts are not available on every system (pstree, loginctl, tty). This was the only thing that worked for me on a ten years old BusyBox/OpenWrt router that I'm currently using as a blacklist DNS server. It runs a script with an auto-update feature. Running from crontab, it sends an email out.
[ -z "$TERM" ] || [ "$TERM" = "dumb" ] && echo 'Crontab' || echo 'Interactive'
In an interactive shell the $TERM-variable returns the value vt102 for me. I included the check for "dumb" since #edoceo mentioned it worked for him. I didn't use '==' since it's not completely portable.
I also liked the idea from Tal, but also see the risk of having undefined returns. I ended up with a slightly modified version, which seems to work very smooth in my opinion:
CRON="$( pstree -s $$ | grep -c cron )"
So you can check for $CRON being 1 or 0 at any time.