I am working on a small script that checks if a host is up or down.
until [ "$STATUS" -eq "0" ]
do
ping -c 1 192.168.0.3
echo The host is down
STATUS=`echo $?`
done
It is supposed to change the status to 0 if it pings a host that is up and exit the until loop. But it doesnt. Even if I echo out the value of $? the value is always zero.
Can anyone help me figure this out please? :)
Thanks in advance
You have echo The host is down after ping command. So $? takes the exit status of the echo command not the ping command.
ping -c 1 192.168.0.3
STATUS=$?
if [ $STATUS -ne 0 ]; then
echo "The host is down"
fi
You placed echo after saving the status that's why you always get 0:
ping -c 1 192.168.0.3
echo The host is down ## Always changes $? to 0
STATUS=`echo $?`
One better way to do it could be:
until ping -c 1 192.168.0.3; do
echo "The host is down"
done
Longer version:
until ping -c 1 192.168.0.3; STATUS=$?; [ "$STATUS" -eq "0" ]; do
echo "The host is down"
done
Related
I'm really sorry to annoy to you again with my problem but it seems I'm about to finish. My goal is to create a bash-script that checks if a IP-address is still online or a scrub is in progress and if not that my systems shuts down. My script, which is currently in use, looks like this
#!/bin/bash
hosts=(
10.10.0.100 #Client 1
10.10.0.101 #Client 2
10.10.0.102 #Client 3
10.10.0.103 #Client 4
10.10.0.104 #Client 5
)
for host in "${hosts[#]}"; do
if ping -c 1 -i 1 "$host" >/dev/null; then
echo "No Shutdown - At least one PC ($host) is online"
exit 0
fi
done
echo "No PC is online - Shutdown"
bash shutdown -p now
I did some research and found the following command, to check if my scrub is in progress
if [ $(zpool status | grep 'scrub in progress') ]; then
echo "No Shutdown - Scrub in progess"
exit 0
fi
But i have problems in combining these two. I want my script to first check the IPs and if they all are offline then check for a scrub before it shuts down the machine. So both if-cases have to be false (ips offline and scrub not in progress) but they should be processed chronological and if the first if-case returns a IP which is online the script should stop.
Maybe somebody can help me?
To check if a command output contains a string, just:
if zpool status | grep -q 'scrub in progress'; then
The [ $(zpool status | grep 'scrub in progress') ] is invalid. The $( .. ) will expand to multiple words and will run [ scrub in progress ]. Because in is not a valid operator for [, then [ will print an error message and exit with 2. Just check the error status of grep.
For me, the answer is trivial:
hosts=(
10.10.0.100 #Client 1
10.10.0.101 #Client 2
10.10.0.102 #Client 3
10.10.0.103 #Client 4
10.10.0.104 #Client 5
)
for host in "${hosts[#]}"; do
if ping -c 1 -i 1 "$host" >/dev/null; then
echo "No Shutdown - At least one PC ($host) is online"
exit 0
fi
done
if $(zpool status | grep 'scrub in progress'); then
echo "No Shutdown - Scrub in progess"
exit 0
fi
echo "No PC is online and Scrub is not in progress - Shutdown"
shutdown -p now
Or did I miss the point?
Mind a couple of corrections inside of your code: remove the square brackets around the if test and remove the bash before shutdown.
You can negate the exit status by using !
if ! ping -c 1 -i 1 "$host" >/dev/null; then
if ! [[ $(zpool status | grep 'scrub in progress') ]]; then
echo "No PC is online - Shutdown"
bash shutdown -p now
fi
fi
## Add the rest of the script here if both conditions are true.
That basically means both condition are false, meaning there is no host up and scrub is not in progress, the opposite without the !
Check if both conditions are true just remove the !
if ping -c 1 -i 1 "$host" >/dev/null; then
if [[ $(zpool status | grep 'scrub in progress') ]]; then
echo "No Shutdown - At least one PC ($host) is online"
exit 0
fi
fi
Check if hosts are up but scrub is not running.
if ping -c 1 -i 1 "$host" >/dev/null; then
if ! [[ $(zpool status | grep 'scrub in progress') ]]; then
##: Add/run/execute your code here to start scrub.
fi
fi
If Nesting is what you want that would be something like.
for host in "${hosts[#]}"; do
if ping -c 1 -i 1 "$host" >/dev/null; then
echo "No Shutdown - At least one PC ($host) is online"
exit 0
elif ! ping -c 1 -i 1 "$host" >/dev/null; then
if ! [[ $(zpool status | grep 'scrub in progress') ]]; then
echo "No PC is online - Shutdown"
bash shutdown -p now
fi
fi
done
You can add the test for zpool inside the first if-statement.
for host in "${hosts[#]}"; do
if ping -c 1 -i 1 "$host" >/dev/null; then
if [[ $(zpool status | grep 'scrub in progress') ]]; then
echo "No Shutdown - At least one PC ($host) is online"
exit 0
fi
fi
elif ! ping -c 1 -i 1 "$host" >/dev/null; then
if ! [[ $(zpool status | grep 'scrub in progress') ]]; then
echo "No PC is online - Shutdown"
bash shutdown -p now
fi
fi
done
The first example set of if-statement should be enough though.
see help test
I have a little problem with my bash script
i got a school project where i have to make a bash script to check if the host is up every 5 minuttes and if fails send email
i had problems with the "fi" statement but fixed the error.
now when i run the script i get an error: line 17 to many arguments"
it initiate the ping command (my Anti virus is blocking the ICMP, so i know the ping lines work)
#!/bin/bash
#Server-status script
FAILS=0
EMAIL_ADDRESS="Critical-error#gruppe4.net" ##Email capabilities
SERVER="192.168.1.1" ###Host to check
SLEEP=300 ###Defining Sleep
while true; do
ping -c 1 $SERVER >/dev/null 2>&1
if [ $? -ne 0 ] ; then #if ping exits nonzero...
FAILS=$"[FAILS + 1]"
else
FAILS=0
fi
if [ $FAILS -gt 4 ]; then
FAILS=0
echo "Server $SERVER is offline!" \
| mail -s "Server offline" "$EMAIL_ADDRESS"
fi
sleep $SLEEP #check again in SLEEP seconds
done
use declare -i to use FAILS as integer and initialize to 0
declare -i FAILS=0
then sum 1
FAILS=$FAILS+1
here is my code(I've commented the mail commmand):
#!/bin/bash
#Server-status script
declare -i FAILS=0
EMAIL_ADDRESS="Critical-error#gruppe4.net" ##Email capabilities
SERVER="192.168.1.1" ###Host to check
SLEEP=1 ###Defining Sleep
echo "1-FAILS[$FAILS]"
while true; do
ping -c 1 $SERVER >/dev/null 2>&1
if [ $? -ne 0 ] ; then #if ping exits nonzero...
FAILS=$FAILS+1
else
FAILS=0
fi
echo "2-FAILS[$FAILS]"
if [ $FAILS -gt 1 ]; then
FAILS=0
echo "Server $SERVER is offline!" # \ | mail -s "Server offline" "$EMAIL_ADDRESS"
fi
sleep $SLEEP #check again in SLEEP seconds
done
output:
sh-4.3$ bash -f main.sh
1-FAILS[0]
2-FAILS[1]
2-FAILS[2]
Server 192.168.1.1 is offline!
2-FAILS[1]
2-FAILS[2]
Server 192.168.1.1 is offline!
2-FAILS[1]
2-FAILS[2]
Server 192.168.1.1 is offline!
2-FAILS[1]
I hope this can help
Regards
Claudio
You are expanding the $FAILS variable with content [FAILS + 1], getting an invalid [] syntax.
Change FAILS=$"[FAILS + 1]" to:
FAILS=$((FAILS+1))
I have a bash script that connects to servers via SSH to run a command. The script gets the IP address from a file.
Problem: if I have 500 IPs in the file, I don't want to simultaneously open or try to open 500 connections. I want to do, lets say, 10 at a time in order to save resources.
How do I run the command via SSH 10 servers at a time?
Here is my script:
#/bin/bash
nodes="big_list_of_nodes.txt"
while read node; do
# Running in background
(uptime=`ssh -o ConnectTimeout=5 $node uptime 2>&1`
if [ $? -eq 0 ]; then
echo "$node uptime: $uptime"
else
echo "Connection timeout for node $node"
fi) &
done < $nodes
# Wait for all jobs to finish
wait
You want to write a function to do all the work for you that takes an IP address as an argument. Then use parallel to read in the file and distribute work to the function:
function get_uptime()
{
node=$1
uptime=`ssh -o ConnectTimeout=5 $node uptime 2>&1`
if [ $? -eq 0 ]; then
echo "$node uptime: $uptime"
else
echo "Connection timeout for node $node"
fi
}
export -f get_uptime
parallel -j 10 --will-cite -a big_list_of_nodes.txt get_uptime
The -j argument tells parallel how many jobs can be active at a time.
I was able to figure it out and make it work.
I add N lines to an array, then I process everything in that array. Then the array is empty and the process is repeated.
This way, you can have a file with hundreds of hostnames or IP address and process in N chunks.
#/bin/bash
nodes=`cat big_list_of_nodes.txt`
for node in $nodes
do
array+=($node)
if [ ${#array[#]} -gt 10 ]; then
for n in ${array[#]}
do
(uptime=`ssh -o ConnectTimeout=5 $n uptime 2>&1`
if [ $? -eq 0 ]; then
echo "$n uptime: $uptime"
else
echo "Connection timeout for node $n"
fi) &
done
wait
array=()
fi
done
if [ ${#array[#]} -gt 0 ]; then
for n in ${array[#]}
do
(uptime=`ssh -o ConnectTimeout=5 $n uptime 2>&1`
if [ $? -eq 0 ]; then
echo "$n uptime: $uptime"
else
echo "Connection timeout for node $n"
fi) &
done
wait
fi
I want to run a bash-script on my raspi.
The script's purpose is to check one device in my network for availability (with ping).
If this device is responding, script should end.
If it's not responding it has to go further and check the availability of 3 specific devices: if one device of that 3 is responding, then send a mail; if none of these devices is responding, then do nothing.
I hope it is recognizable what I've done so far:
#!/bin/bash
array=(192.168.xxx.xxx 192.168.xxx.xxx)
ping -c 1 192.168.xxx.xxx
if [$? -eq 0]; then exit 0
else
for devices in "${array[#]}"
do ping -c 1 $devices &> /dev/null
if [ $? -eq 0 ]; then exit 0
fi
fi
done
/usr/sbin/sendmail foo#bar.com < /home/pi/scripts/email.txt
I'm pretty stuck right now, because my script skills are frightening bad.
Some comments:
#!/bin/bash
array=(192.168.xxx.xxx 192.168.xxx.xxx)
# a way to simplify first if:
ping -c 1 192.168.xxx.xxx && exit 0
for devices in "${array[#]}"; do
# you want send mail if ping is ok
if ping -c 1 $devices &> /dev/null; then
/usr/sbin/sendmail foo#bar.com < /home/pi/scripts/email.txt
exit 0
fi
done
Two errors in your code:
if [$? -eq 0]; then should be if [ $? -eq 0 ]; then
The fi before done should be moved outside the for loop.
Example:
array=(192.168.xxx.xxx 192.168.xxx.xxx)
ping -c 1 192.168.xxx.xxx
if [ $? -eq 0 ]; then
exit 0
else
for devices in "${array[#]}";do
ping -c 1 $devices &> /dev/null
if [ $? -eq 0 ]; then
exit 0
fi
done
fi
Suggested improvements:
Double quoting your variables is a good practice
Use of if [[ $? -eq 0 ]]; then is better than if [ $? -eq 0 ]; then in bash
I want to write a script, that would keep checking if any of the devices in network, that should be online all day long, are really online. I tried to use ping, but
if [ "`ping -c 1 some_ip_here`" ]
then
echo 1
else
echo 0
fi
gives 1 no matter if I enter valid or invalid ip address. How can I check if a specific address (or better any of devices from list of ip addresses) went offline?
Ping returns different exit codes depending on the type of error.
ping 256.256.256.256 ; echo $?
# 68
ping -c 1 127.0.0.1 ; echo $?
# 0
ping -c 1 192.168.1.5 ; echo $?
# 2
0 means host reachable
2 means unreachable
You don't need the backticks in the if statement. You can use this check
if ping -c 1 some_ip_here &> /dev/null
then
echo "success"
else
echo "error"
fi
The if command checks the exit code of the following command (the ping). If the exit code is zero (which means that the command exited successfully) the then block will be executed. If it return a non-zero exit code, then the else block will be executed.
I can think of a one liner like this to run
ping -c 1 127.0.0.1 &> /dev/null && echo success || echo fail
Replace 127.0.0.1 with IP or hostname, replace echo commands with what needs to be done in either case.
Code above will succeed, maybe try with an IP or hostname you know that is not accessible.
Like this:
ping -c 1 google.com &> /dev/null && echo success || echo fail
and this
ping -c 1 lolcatz.ninja &> /dev/null && echo success || echo fail
There is advanced version of ping - "fping", which gives possibility to define the timeout in milliseconds.
#!/bin/bash
IP='192.168.1.1'
fping -c1 -t300 $IP 2>/dev/null 1>/dev/null
if [ "$?" = 0 ]
then
echo "Host found"
else
echo "Host not found"
fi
This is a complete bash script which pings target every 5 seconds and logs errors to a file.
Enjoy!
#!/bin/bash
FILE=errors.txt
TARGET=192.168.0.1
touch $FILE
while true;
do
DATE=$(date '+%d/%m/%Y %H:%M:%S')
ping -c 1 $TARGET &> /dev/null
if [[ $? -ne 0 ]]; then
echo "ERROR "$DATE
echo $DATE >> $FILE
else
echo "OK "$DATE
fi
sleep 5
done
FYI,
I just did some test using the method above and if we use multi ping (10 requests)
ping -c10 8.8.8.8 &> /dev/null ; echo $?
the result of multi ping command will be "0" if at least one of ping result reachable,
and "1" in case where all ping requests are unreachable.
up=`fping -r 1 $1 `
if [ -z "${up}" ]; then
printf "Host $1 not responding to ping \n"
else
printf "Host $1 responding to ping \n"
fi
for i in `cat Hostlist`
do
ping -c1 -w2 $i | grep "PING" | awk '{print $2,$3}'
done
This seems to work moderately well in a terminal emulator window. It loops until there's a connection then stops.
#!/bin/bash
# ping in a loop until the net is up
declare -i s=0
declare -i m=0
while ! ping -c1 -w2 8.8.8.8 &> /dev/null ;
do
echo "down" $m:$s
sleep 10
s=s+10
if test $s -ge 60; then
s=0
m=m+1;
fi
done
echo -e "--------->> UP! (connect a speaker) <<--------" \\a
The \a at the end is trying to get a bel char on connect. I've been trying to do this in LXDE/lxpanel but everything halts until I have a network connection again. Having a time started out as a progress indicator because if you look at a window with just "down" on every line you can't even tell it's moving.
I liked the idea of checking a list like:
for i in `cat Hostlist`
do
ping -c1 -w2 $i | grep "PING" | awk '{print $2,$3}'
done
but that snippet doesn't care if a host is unreachable, so is not a great answer IMHO.
I ran with it and wrote
for i in `cat Hostlist`
do
ping -c1 -w2 $i >/dev/null 2>&1 ; echo $i $?
done
And I can then handle each accordingly.
check host every one second and send message when host is reach
while :;do ping -c 1 -w 1 -q 8.8.8.8 &>/dev/null && /root/telegram-send.sh "Host reacheble now" && break || sleep 1;done