I've been using monit for a little while, but I want to alarm if a file exists. This is the opposite use case from the main documentation.
Here's the doc says:
IF [DOES] NOT EXIST [[<X>] <Y> CYCLES] THEN action [ELSE IF SUCCEEDED [[<X>] <Y> CYCLES] THEN action]
action is a choice of "ALERT", "RESTART", "START", "STOP", "EXEC" or "UNMONITOR".
This gives me the recipe for "freak out if file is missing". But I want to "freak out if the file's there". And the choice of actions implies there's no "do nothing" action. I could shell out to a no-op, but that's really silly for the standard case of "do nothing".
I guessed some basic cases:
IF EXISTS THEN alarm
IF EXIST THEN ALARM
So, is there a standard way to do IF IT DOES EXIST?
I recently was looking for the same solution as you and unfortunately, I was unable to discover a way of doing this in monit.
My situation differs slightly from yours so I ended up alarming if the file did not exist, and executed a shell script if it did. Like you, I did not want to spawn a shell just because the file did not exist, and having "file does not exist" show up in /var/log/messages isn't a big deal for me.
I know you said that you could shell out to a no-op so you probably don't need the following but I am adding it for those who might have the same issue and not know how to do it.
check file testfile with path /path/to/file
if not exist then exec "/bin/bash -c 'echo dne > /dev/null'" else if succeeded then alarm
Note that you must exec /bin/bash to write the output of echo to /dev/null or monit will literally echo "dne > /dev/null"
Edit: As it was brought to my attention by disasteraverted, newer versions of Monit use alert rather than alarm, so the check would look like this:
check file testfile with path /path/to/file
if not exist then exec "/bin/bash -c 'echo dne > /dev/null'" else if succeeded then alert
since monit 5.21.0, alterting on existence is directly supported:
check file testfile with path /path/to/file
if exist then alert
see in changelog https://mmonit.com/monit/changes/#5.21.0
Please check with :
check program not_exist_file_root_test with path "/bin/ls /root/test"
if status = 0 then alert
or
check program not_exist_file_root_test with path /bin/sh -c "test -f /root/test"
if status = 0 then alert
My 2 cents
renab, your check should end with "then alert" not "then alarm" at least in my version (5.2.5).
testfile with path /path/to/file
if not exist then exec "/bin/bash -c 'echo dne > /dev/null'" else if succeeded then alert
Related
I have a python script that I use as to check certain system conditions to alert on using monit.
This script prints a buch of stuff during execution to stdout which I want to capture in a log file.
How should I configure the monit conf script, such that I can capture both the stdout and stderr of this script and at the same time alerting on the exit status of the script. The monit alert should also included the stdout/stderr for the alert events.
This is what I tried
#/etc/monit/conf/myprogram.conf
check program my_program with path "/usr/bin/python -u /opt/program/my_program.py > my_prgoram.log 2&>1"
if status !=0 alert
But I see that the monit always thinks that the program is reporting status=0 even when then it exists with error code 1.
What am i doing wrong?
$MONIT_DESCRIPTION contains stderr
Try this:
#/etc/monit/conf/myprogram.conf
check program my_program with path "/bin/bash -c '/usr/bin/python -u /opt/program/my_program.py > my_prgoram.log 2&>1'"
if status !=0 alert
When creating a PKGBUILD file one can execute hooks at pre_install(), post_install(), etc.
I now have a custom arch linux pacman package that I need some custom checks done before it is installed to determine if it is safe to install or not.
I would like to run my test in the pre_istall() script and have pacman abort the installation if I say so in the script.
So, how can this be accomplished? So far all I have accomplished is getting an error message in the log but pacman continues with the istall...
I would not recommend this as it sounds like a code smell: in my opinion the pre_install() hook is designed to perform actions before package files are actually installed on your drive, but it is not meant to check whether the package should be installed.
In my opinion, such a check belongs to some other place out of the package.
You could call a command, which returns a non-zero exit-code, to cancel the build process. The simplest command I could think of is sh -c "exit 1", since just exit 1 results in an immediate exit without any proper cleanup.
Here is a simple example that checks if a file exists and cancels the build process if not:
prepare() {
if ! [ -f "/usr/bin/ffmpeg" ]; then
echo "Error: FFmpeg executable '/usr/bin/ffmpeg' is missing."
sh -c "exit 1"
fi
}
However, galaux is right. Usually such checks should happen upstream.
I have very simple script in monit:
check file reload_nginx with path /srv/www/site/shared/pids/reload_nginx
if not exist then exec "/bin/bash -c 'echo \"OK\"'" else if succeeded then exec "/bin/bash -c 'service nginx reload; rm /srv/www/site/shared/pids/reload_nginx'"
Monit shows that it's in "accessible" state.
But script does ... nothing.
File still exists on that path. No messages in syslog.
I've tried to change exec to alerts and echos - and still received nothing. I can't even say, whether checks are performed or not.
How to deal with it?
So, ok, i found the answer.
[if succeeded] branch in monit executed only when state of check CHANGED from "Failed" to "Succeeded". If check is succeeded at the start of monitoring - that branch wan't be called.
I'm new to Apache SVN and I need some help to use a pre-commit script to filter which files are being upload to my repository.
I was searching a lot and found this script on another question, but it didn't work for me.
#!/bin/bash
REPOS=$1
TXN=$2
AWK=/usr/bin/awk
SVNLOOK="/usr/bin/svnlook";
#Put all the restricted formats in variable FILTER
FILTER=".(sh|xls|xlsx|exe|xlsm|XLSM|vsd|VSD|bak|BAK|class|CLASS)$"
# Figure out what directories have changed using svnlook.
FILES=`${SVNLOOK} changed -t ${REPOS} ${TXN} | ${AWK} '{ print $2 }'` > /dev/null
for FILE in $FILES; do
#Get the base Filename to extract its extension
NAME=`basename "$FILE"`
#Get the extension of the current file
EXTENSION=`echo "$NAME" | cut -d'.' -f2-`
#Checks if it contains the restricted format
if [[ "$FILTER" == *"$EXTENSION"* ]]; then
echo "Your commit has been blocked because you are trying to commit a restricted file." 1>&2
echo "Please contact SVN Admin. -- Thank you" 1>&2
exit 1
fi
done
exit 0
If I try to use svnlook changed -t repodirectory it didn't work because had a missing subcommand.
I overwrote my pre-commit.tmpl but it didn't work, can someone help me?
First - seems you incorrectly use svnlook. It should has parameters:
svnlook changed ${REPOS} -t ${TXN}
-t means 'read from transaction' and TXN - transaction name itself.
Second - not sure if I understand correctly, but hook file should has name pre-commit not pre-commit.tmpl
Third - pre-commit should has correct rights. For tests try a+rwx
update. It is not easy to obtain transaction object for tests, but you can use svnlook -r <revision> <repositiry_path> and experiment on already commited revisions.
I am looking for a multiplatform solution that would allow me to check if scp command is available.
The problem is that scp does not have a --version command line and when called without parameters it will return with exit code 1 (error).
Update: in case it wasn't clear, by multiplatform I mean a solution that will work on Windows, OS X and Linux without requiring me to install anything.
Use the command which scp. It lets you know whether the command is available and it's path as well. If scp is not available, nothing is returned.
#!/bin/sh
scp_path=`which scp || echo NOT_FOUND`
if test $scp_path != "NOT_FOUND"; then
if test -x ${scp_path}; then
echo "$scp_path is usable"
exit 0
fi
fi
echo "No usable scp found"
sh does not have a built-in which, thus we rely on a system provided which command. I'm not entirely sure if the -x check is needed - on my system which actually verifies if the found file is executable by the user, but this may not be portable. On the rare case where the system has no which command, one can write a which function here.