I am making a menu for myself, because sometimes I need to search (Or NMAP which port).
I want to do the same as running the command in the command line.
Here is a piece of my code:
nmap $1 | grep open | while read line; do
serviceport=$(echo $line | cut -d' ' -f1 | cut -d'/' -f1);
if [ $i -eq $choice ]; then
echo "Running command: netcat $1 $serviceport";
netcat $1 $serviceport;
fi;
i=$(($i+1));
done;
It is closing immediately after it scanned everything with nmap.
Don't use FD 0 (stdin) for both your read loop and netcat. If you don't distinguish these streams, netcat can consume content emitted by the nmap | grep pipeline rather than leaving that content to be read by read.
This has a few undesirable effects: Further parts of the while/read loop don't get executed, and netcat sees a closed stdin stream and exits when the pipeline's contents are consumed (so you don't get interactive control of netcat, if that's what you're trying to accomplish). An easy way to work around this issue is to feed the output of your nmap pipeline in on a non-default file descriptor; below, I'm using FD 3.
There's a lot wrong with this code beyond the scope of the question, so please don't consider the parts I've copied-and-pasted an endorsement, but:
while read -r -u 3 line; do
serviceport=${line%% *}; serviceport=${serviceport##/*}
if [ "$i" -eq "$choice" ]; then
echo "Running command: netcat $1 $serviceport"
netcat "$1" "$serviceport"
fi
done 3< <(nmap "$1" | grep open)
Related
I was working on a script that would keep monitoring login to my server or laptop via ssh.
this was the code that I was working with.
slackmessenger() {
curl -X POST -H 'Content-type: application/json' --data '{"text":"'"$1"'"}' myapilinkwashere
## removed it the api link due to slack restriction
}
while true
do
tail /var/log/auth.log | grep sshd | head -n 1 | while read LREAD
do
echo ${LREAD}
var=$(tail -f /var/log/auth.log | grep sshd | head -n 1)
slackmessenger "$var"
done
done
The issue I'm facing is that it keeps sending the old logs due to the while loop. can there be a condition that the loop only sends the new entries/updated enter as opposed to sending the old one over and over again. could not think of a condition that would skip the old entries and only shows old one.
Instead of using head -n 1 to extract a line at a time, iterate over the filtered output of tail -f /var/log/auth.log | grep sshd and process each line once as it comes through.
#!/usr/bin/env bash
# ^^^^- this needs to be a bash script, not a sh script!
case $BASH_VERSION in '') echo "Needs bash, not sh" >&2; exit 1;; esac
while IFS= read -r line; do
printf '%s\n' "$line"
slackmessenger "$line"
done < <(tail -f /var/log/auth.log | grep --line-buffered sshd)
See BashFAQ #9 describing why --line-buffered is necessary.
You could also write this as:
#!/usr/bin/env bash
case $BASH_VERSION in '') echo "Needs bash, not sh" >&2; exit 1;; esac
tail -f /var/log/auth.log |
grep --line-buffered sshd |
tee >(xargs -d $'\n' -n 1 slackmessenger)
The script monitors incoming HTTP messages and forwards them to a monitoring application called zabbix, It works fine, however after about 1-2 days it stops working. Heres what I know so far:
Using pgrep i see the script is still running
the logfile file gets updated properly (first command of script)
The FIFO pipe seems to be working
The problem must be somewhere in WHILE loop or tail command.
Im new at scripting so maybe someone can spot the problem right away?
#!/bin/bash
tcpflow -p -c -i enp2s0 port 80 | grep --line-buffered -oE 'boo.php.* HTTP/1.[01]' >> /usr/local/bin/logfile &
pipe=/tmp/fifopipe
trap "rm -f $pipe" EXIT
if [[ ! -p $pipe ]]; then
mkfifo $pipe
fi
tail -n0 -F /usr/local/bin/logfile > /tmp/fifopipe &
while true
do
if read line <$pipe; then
unset sn
for ((c=1; c<=3; c++)) # c is no of max parameters x 2 + 1
do
URL="$(echo $line | awk -F'[ =&?]' '{print $'$c'}')"
if [[ "$URL" == 'sn' ]]; then
((c++))
sn="$(echo $line | awk -F'[ =&?]' '{print $'$c'}')"
fi
done
if [[ "$sn" ]]; then
hosttype="US2G_"
host=$hosttype$sn
zabbix_sender -z nuc -s $host -k serial -o $sn -vv
fi
fi
done
You're inputting from the fifo incorrectly. By writing:
while true; do read line < $pipe ....; done
you are closing and reopening the fifo on each iteration of the loop. The first time you close it, the producer to the pipe (the tail -f) gets a SIGPIPE and dies. Change the structure to:
while true; do read line; ...; done < $pipe
Note that every process inside the loop now has the potential to inadvertently read from the pipe, so you'll probably want to explicitly close stdin for each.
#!/bin/bash
ip route add 10.105.8.100 via 192.168.1.100
date
cat /home/xxx/Documents/list.txt | while read output
do
ping="ping -c 3 -w 3 -q 'output'"
if $ping | grep -E "min/avg/max/mdev" > /dev/null; then
echo 'connection is ok'
else
echo "router $output is down"
then
cat /home/xxx/Documents/roots.txt | while read outputs
do
cd /home/xxx/Documents/routers
php rebootRouter.php "outputs" admin admin
done
fi
done
The other documents are:
lists.txt
10.105.8.100
roots.txt
192.168.1.100
when i run the script, the result is a reboot of the router am trying to ping. It doesn't ping.
Is there a problem with the bash script.??
If your files only contain a single line, there's no need for the while-loop, just use read:
read -r router_addr < /home/xxx/Documents/list.txt
# the grep is unnecessary, the return-code of the ping will be non-zero if the host is down
if ping -c 3 -w 3 -q "$router_addr" &> /dev/null; then
echo "connection to $router_addr is ok"
else
echo "router $router_addr is down"
read -r outputs < /home/xxx/Documents/roots.txt
cd /home/xxx/Documents/routers
php rebootRouter.php "$outputs" admin admin
fi
If your files contain multiple lines, you should redirect the file from the right-side of the while-loop:
while read -r output; do
...
done < /foo/bar/baz
Also make sure your files contain a newline at the end, or use the following pattern in your while-loops:
while read -r output || [[ -n $output ]]; do
...
done < /foo/bar/baz
where || [[ -n $output ]] is true even if the file doesn't end in a newline.
Note that the way you're checking for your routers status is somewhat brittle as even a single missed ping will force it to reboot (for example the checking computer returns from a sleep-state just as the script is running, the ping fails as the network is still down but the admin script succeeds as the network just comes up at that time).
Is it possible to write a script that does not proceed till a given line appears in a particular file?
For example I want to do something like this:
CANARY_LINE='Server started'
FILE='/var/logs/deployment.log'
echo 'Waiting for server to start'
.... watch $FILE for $CANARY_LINE ...
echo 'Server started'
Basically, a shell script that watches a file for line (or regex).
tail -n0 -f path_to_my_log_file.log | sed '/particular_line/ q'
You can use the q flag while parsing the input via sed. Then sed will interrupt tail as soon as Server started appears in /var/logs/deployment.log.
tail -f /var/logs/deployment.log | sed '/Server started/ q'
Another way to do the same thing
( tail -f -n0 /var/logs/deployment.log & ) | grep -q "Server Started"
Previous answer (works but not as efficient than this one)
We have to be careful with loops.
For example if you want to check for a file to start an algorithm you've probably have to do something like that:
FILE_TO_CHECK="/var/logs/deployment.log"
LINE_TO_CONTAIN="Server started"
SLEEP_TIME=10
while [ $(cat FILE_TO_CHECK | grep "${LINE_TO_CONTAIN}") ]
do
sleep ${SLEEP_TIME}
done
# Start your algorithm here
But, in order to prevent an infinite loop you should add some bound:
FILE_TO_CHECK="/var/logs/deployment.log"
LINE_TO_CONTAIN="Server started"
SLEEP_TIME=10
COUNT=0
MAX=10
while [ $(cat FILE_TO_CHECK | grep "${LINE_TO_CONTAIN}") -a ${COUNT} -lt ${MAX} ]
do
sleep ${SLEEP_TIME}
COUNT=$(($COUNT + 1))
done
if [ ! $(cat FILE_TO_CHECK | grep "${LINE_TO_CONTAIN}") ]
then
echo "Let's go, the file is containing what we want"
# Start your algorithm here
else
echo "Timed out"
exit 10
fi
CANARY_LINE='Server started'
FILE='/var/logs/deployment.log'
echo 'Waiting for server to start'
grep -q $CANARY_LINE <(tail -f $FILE)
echo 'Server started'
Source: adapted from How to wait for message to appear in log in shell
Try this:
#!/bin/bash
canary_line='Server started'
file='/var/logs/deployment.log'
echo 'Waiting for server to start'
until grep -q "${canary_line}" "${file}"
do
sleep 1s
done
echo 'Server started'
Adjust sleep's parameter to your taste.
If the line in the file needs to match exactly, i.e. the whole line, change grep's second parameter to "^${canary_line}$".
If the line contains any characters that grep thinks are special, you're going to have to solve that... somehow.
I've been trying for a couple nights to get this Script to run with no luck. I'm trying to write a script using Bash that allows a user to paste a block of text, and the script will grep out the valid IP addresses from the text, and automatically ping them in order.
So far, after much modification, I'm stuck at this point:
#!/bin/sh
echo Paste Text with IP Addresses
read inputtext
echo "$inputtext">inputtext.txt
grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}" inputtext.txt > address.txt
awk '{print $1}' < address.txt | while read ip; do
if ping -c1 $ip >/dev/null 2>&1; then
echo $ip IS UP
else
echo $ip IS DOWN
fi
done
rm inputtext.txt
rm address.txt
After running this script, the user is prompted as desired, and if an IP address was included in the first line of text, the ping check will succeed, but then all the text after that line will be spat out onto the following command prompt. So it seems that my issue lies in when I read from user input. The only part that is being read is the first line, and once a break is encountered, the script does not considered any lines past the first in its work.
As written, you just need an outer loop to actually read each line of user input.
#!/bin/sh
echo Paste Text with IP Addresses
while read -r inputtext
do
echo "$inputtext">inputtext.txt
grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}" inputtext.txt > address.txt
awk '{print $1}' < address.txt | while read ip; do
if ping -c1 $ip >/dev/null 2>&1; then
echo $ip IS UP
else
echo $ip IS DOWN
fi
done
rm inputtext.txt
rm address.txt
done
However, you can actually simplify this much further and eliminate the temporary files.
#!/bin/sh
echo Paste Text with IP Addresses
while read -r inputtext
do
ip=$(echo "$inputtext" | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}" | awk '{print $1}')
if ping -c1 $ip >/dev/null 2>&1; then
echo $ip IS UP
else
echo $ip IS DOWN
fi
done