I'm trying to detect if 1 user has 2 terminal sessions open.
How can this be achieved?
What I tried is the following:
linuxName="$(id -u -n)"
for user in "$#"; do
if echo "$who" | grep -q "$linuxName"; then
echo "[WARNING] You're already logged in";
closeSessionIfNotRoot
fi;
done;
sort count and filter these that have more then 2.
id -u -n | sort | uniq -c | awk '$1 > 2'
#!/usr/bin/bash
linuxName="$(id -un)"
for user in "$#"; do
process_counter=$(pgrep -u "$user" bash 2>&1 | wc -l)
if [[ "$user" == $(who | grep -o "$linuxName") ]]; then
echo "[WARNING] You're already logged in $user"
if [[ "$process_counter" -gt 1 ]]; then
((process_counter--))
pgrep -u "$user" bash | tail -"$process_counter" |
xargs -I % kill -9 %
echo "closed other terminals: $user"
fi
fi
done
script +arguments[in this case, users_names], example, ./script alex zara sophia
Explain answer
Count terminals open by user and save to variable process_counter
process_counter=$(pgrep -u "$user" bash 2>&1 | wc -l)
2>1 REDIRECTS output error to NO SHOW. this in case you wrote a user_name that doesn't exist in the system.
pgrep -u $user bash | wc -l returns number of terminals open. u $user is for returning the process from that user, so this uniq.
pgrep shows the process you are searching for,e.g., pgreg bash returns a lists of process IDs
returns:
363570
369836
370113
this checks if the $user --> ./file alex zara is the same as in terminal $linuxName
[[ "$user" == $(who | grep -o "$linuxName") ]]
grep -o only returns the username alex instead of alex :1 2021-07....
[[ ]] is to make comparisons in bash
xargs is for pasing previous argument to a loop
tail -"$process_counter" | xargs -I % kill -9 %
tail -$process_counter is for showing the last terminals open
363570
369836 #return only this
370113 #return only this
remember that we REST minus 1 to process_counter because we want to leave 1 terminal open, this is done with ((process_counter--)).
So 3 terminals open - 1 terminal = 2 terminals to close.
now we loop with XARGS
363570
369836 #CLOSE THIS kill -9 369836
370113 #CLOSE THIS kill -9 370113
-I arguments tells xargs to assign a variable, represented with symbol %. but this symbol can be anything,like #,$, and then what we want to do is kill each process, so that's why kill -9 %
Check limits.conf which is configuration file for the pam_limits module.
In that file, you can define maxlogins as the maximum number of logins for a user (this limit does not apply to user with uid=0)
See https://www.man7.org/linux/man-pages/man5/limits.conf.5.html.
Related
I want to check if my VPN is connected to a specific country. The VPN client has a status option but sometimes it doesn't return the correct country, so I wrote a script to check if I'm for instance connected to Sweden. My script looks like this:
#!/bin/bash
country=Sweden
service=expressvpn
while true; do
if ((curl -s https://www.iplocation.net/find-ip-address | grep $country | grep -v "grep" | wc -l) > 0 )
then
echo "$service connected!!!"
else
echo "$service not connected!"
$service connect $country
fi;
sleep 5;
done
The problem is, it always says "service connected", even when it isn't. When I enter the curl command manually, wc -l returns 0 if it didn't find Sweden and 1 when it does. What's wrong with the if statement?
Thank you
Peter
(( )) enters a math context -- anything inside it is interpreted as a mathematical expression. (You want your code to be interpreted as a math expression -- otherwise, > 0 would be creating a file named 0 and storing wc -l's output in that file, not comparing the output of wc -l to 0).
Since you aren't using )) on the closing side, this is presumably exactly what's happening: You're storing the output of wc -l in a file named 0, and then using its exit status (successful, since it didn't fail) to decide to follow the truthy branch of the if statement. [Just adding more parens on the closing side won't fix this, either, since curl -s ... isn't valid math syntax].
Now, if you want to go the math approach, what you can do is run a command substitution, which replaces the command with its output; that is a math expression:
# smallest possible change that works -- but don't do this; see other sections
if (( $(curl -s https://www.iplocation.net/find-ip-address | grep $country | grep -v "grep" | wc -l) > 0 )); then
...if your curl | grep | grep | wc becomes 5, then after the command substitution this looks like:
if (( 5 > 0 )); then
...and that does what you'd expect.
That said, this is silly. You want to know if your target country is in curl's output? Just check for that directly with shell builtins alone:
if [[ $(curl -s https://www.iplocation.net/find-ip-address) = *"$country"* ]]; then
echo "Found $country in output of curl" >&2
fi
...or, if you really want to use grep, use grep -q (which suppresses output), and check its exit status (which is zero, and thus truthy, if and only if it successfully found a match):
if curl -s https://www.iplocation.net/find-ip-address | grep -q -e "$country"; then
echo "Found $country in output of curl with grep" >&2
fi
This is more efficient in part because grep -q can stop as soon as it finds a match -- it doesn't need to keep reading more content -- so if your file is 16KB long and the country name is in the first 1KB of output, then grep can stop reading from curl (and curl can stop downloading) as soon as that first match 1KB in is seen.
The result of the curl -s https://www.iplocation.net/find-ip-address | grep $country | grep -v "grep" | wc -l statement is text. You compare text and number, that is why your if statement does not work.
This might solve your problem;
if [ $(curl -s https://www.iplocation.net/find-ip-address | grep $country | grep -v "grep" | wc -l) == "0" ] then ...
That worked, thank you for your help, this is what my script looks now:
#!/bin/bash
country=Switzerland
service=expressvpn
while true; do
if curl -s https://www.iplocation.net/find-ip-address | grep -q -e "$country"; then
echo "Found $country in output of curl with grep" >&2
echo "$service not connected!!!"
$service connect Russia
else
echo "$service connected!"
fi;
sleep 5;
done
I have this script
#!/bin/bash
npid=$(pgrep -f procname | wc -l)
echo $npid
if [ $npid -lt 3 ];then
service procname start;
fi
When procname is running, it works fine showing the correct number for $npid. It fails when there isn't any procname running. It should return zero, but it returns npid=3, exactly 3. The same problem I see for ps auxw | grep procname | grep -v grep | wc -l as well.
Something trivially wrong I just couldn't figure out, any suggestions ?
* EDIT
# This returns nothing if therisn't a process name poopit running
pgrep -f poopit
# In the case when no process running, below returns zero if typed on a bash cmd line
pgrep -f poopit | wc -l
# If running,
pgrep -f poopit | wc -l
17
# If running, the script $npid shows
19
Welcome, I have a short script to kill processes which works longer than specified time for UIDs bigger than. How to exclude for example mc command from killing?
#!/bin/bash
#
#Put the minimum(!) UID to kill processes
UID_KILL=500
#Put the time in seconds which the process is allowed to run below
KILL_TIME=300
KILL_LIST=`{
ps -eo uid,pid,lstart | tail -n+2 |
while read PROC_UID PROC_PID PROC_LSTART; do
SECONDS=$[$(date +%s) - $(date -d"$PROC_LSTART" +%s)]
if [ $PROC_UID -ge $UID_KILL -a $SECONDS -gt $KILL_TIME ]; then
echo -n "$PROC_PID "
fi
done
}`
#KILLING LOOP
while sleep 1
do
if [[ -n $KILL_LIST ]]
then
kill $KILL_LIST
fi
done
change inner command like this :
ps -eo comm,uid,pid,lstart | tail -n+2 | grep -v '^your_command' | ...
this will exclude 'your_command' from the list.
see STANDARD FORMAT SPECIFIERS in man ps for more about ps -o.
Hello I created a script to kill processes ordered by age however everytime the PIDs are changing... how can I solve this
here is my script
#!/bin/bash
#Argument = -c check -k kill -l list
usage()
{
cat << EOF
usage: $0 options
This script kills all the processes running and leaves the last one sorted by age running.
OPTIONS:
-c checks how many proccess are runnig it needs string argument
-k Kill all the processes and leaves just the last sorted by age running
-l Show the list of procesess to be killed.
EOF
}
CHECK=
KILL=
LIST=
while getopts "hc:k:l:" OPTION
do
case $OPTION in
h)
usage
exit 1
;;
c)
CHECK=$OPTARG
ps -ef | grep -i $CHECK | wc -l
;;
k)
KILL=$OPTARG
T2=$(ps -ef | grep -i "$KILL" | awk '{print $3,$5}' | sort -r +1 | sed 1d |awk '{print $1}')
for f in $T2; do
echo "killing $f"
kill $f
done
;;
l)
LIST=$OPTARG
T2=$(ps -ef | grep -i "$LIST" | awk '{print $3,$5}' | sort -r +1 | sed 1d |awk '{print $1}')
for f in $T2; do
echo "PID $f"
done
;;
?)
usage
exit
;;
esac
done
if [[ -z KILL ]] || [[ -z LIST ]] || [[ -z CHECK ]]
then
usage
exit 1
fi
and also I don't understand why when I call the script with no arguments the help doesn't show up
The PIDs will change if another program is restarting it when it's killed. This is actually pretty common with daemons.
usage is never called because you're checking whether the strings KILL etc. are empty, not the variables. Just add a dollar sign in front of them.
First off, I'm new to this. I have some experience with windows scripting and apple script but not much with bash. What I'm trying to do is grab the PID and %CPU of a specific process. then compare the %CPU against a set number, and if it's higher, kill the process. I feel like I'm close, but now I'm getting the following error:
[[: 0.0: syntax error: invalid arithmetic operator (error token is ".0")
what am I doing wrong? here's my code so far:
#!/bin/bash
declare -i app_pid
declare -i app_cpu
declare -i cpu_limit
app_name="top"
cpu_limit="50"
app_pid=`ps aux | grep $app_name | grep -v grep | awk {'print $2'}`
app_cpu=`ps aux | grep $app_name | grep -v grep | awk {'print $3'}`
if [[ ! $app_cpu -gt $cpu_limit ]]; then
echo "crap"
else
echo "we're good"
fi
Obviously I'm going to replace the echos in the if/then statement but it's acting as if the statement is true regardless of what the cpu load actually is (I tested this by changing the -gt to -lt and it still echoed "crap"
Thank you for all the help. Oh, and this is on a OS X 10.7 if that is important.
I recommend taking a look at the facilities of ps to avoid multiple horrible things you do.
On my system (ps from procps on linux, GNU awk) I would do this:
ps -C "$app-name" -o pid=,pcpu= |
awk --assign maxcpu="$cpu_limit" '$2>maxcpu {print "crappy pid",$1}'
The problem is that bash can't handle decimals. You can just multiply them by 100 and work with plain integers instead:
#!/bin/bash
declare -i app_pid
declare -i app_cpu
declare -i cpu_limit
app_name="top"
cpu_limit="5000"
app_pid=`ps aux | grep $app_name | grep -v grep | awk {'print $2'}`
app_cpu=`ps aux | grep $app_name | grep -v grep | awk {'print $3*100'}`
if [[ $app_cpu -gt $cpu_limit ]]; then
echo "crap"
else
echo "we're good"
fi
Keep in mind that CPU percentage is a suboptimal measurement of application health. If you have two processes running infinite loops on a single core system, no other application of the same priority will ever go over 33%, even if they're trashing around.
#!/bin/sh
PROCESS="java"
PID=`pgrep $PROCESS | tail -n 1`
CPU=`top -b -p $PID -n 1 | tail -n 1 | awk '{print $9}'`
echo $CPU
I came up with this, using top and bc.
Use it by passing in ex: ./script apache2 50 # max 50%
If there are many PIDs matching your program argument, only one will be calculated, based on how top lists them. I could have extended the script by catching them all and avergaing the percentage or something, but this will have to do.
You can also pass in a number, ./script.sh 12345 50, which will force it to use an exact PID.
#!/bin/bash
# 1: ['command\ name' or PID number(,s)] 2: MAX_CPU_PERCENT
[[ $# -ne 2 ]] && exit 1
PID_NAMES=$1
# get all PIDS as nn,nn,nn
if [[ ! "$PID_NAMES" =~ ^[0-9,]+$ ]] ; then
PIDS=$(pgrep -d ',' -x $PID_NAMES)
else
PIDS=$PID_NAMES
fi
# echo "$PIDS $MAX_CPU"
MAX_CPU="$2"
MAX_CPU="$(echo "($MAX_CPU+0.5)/1" | bc)"
LOOP=1
while [[ $LOOP -eq 1 ]] ; do
sleep 0.3s
# Depending on your 'top' version and OS you might have
# to change head and tail line-numbers
LINE="$(top -b -d 0 -n 1 -p $PIDS | head -n 8 \
| tail -n 1 | sed -r 's/[ ]+/,/g' | \
sed -r 's/^\,|\,$//')"
# If multiple processes in $PIDS, $LINE will only match\
# the most active process
CURR_PID=$(echo "$LINE" | cut -d ',' -f 1)
# calculate cpu limits
CURR_CPU_FLOAT=$(echo "$LINE"| cut -d ',' -f 9)
CURR_CPU=$(echo "($CURR_CPU_FLOAT+0.5)/1" | bc)
echo "PID $CURR_PID: $CURR_CPU""%"
if [[ $CURR_CPU -ge $MAX_CPU ]] ; then
echo "PID $CURR_PID ($PID_NAMES) went over $MAX_CPU""%"
echo "[[ $CURR_CPU""% -ge $MAX_CPU""% ]]"
LOOP=0
break
fi
done
echo "Stopped"
Erik, I used a modified version of your code to create a new script that does something similar. Hope you don't mind it.
A bash script to get the CPU usage by process
usage:
nohup ./check_proc bwengine 70 &
bwegnine is the process name we want to monitor 70 is to log only when the process is using over 70% of the CPU.
Check the logs at: /var/log/check_procs.log
The output should be like:
DATE | TOTAL CPU | CPU USAGE | Process details
Example:
03/12/14 17:11 |20.99|98| ProdPROXY-ProdProxyPA.tra
03/12/14 17:11 |20.99|100| ProdPROXY-ProdProxyPA.tra
Link to the full blog:
http://felipeferreira.net/?p=1453
It is also useful to have app_user information available to test whether the current user has the rights to kill/modify the running process. This information can be obtained along with the needed app_pid and app_cpu by using read eliminating the need for awk or any other 3rd party parser:
read app_user app_pid tmp_cpu stuff <<< \
$( ps aux | grep "$app_name" | grep -v "grep\|defunct\|${0##*/}" )
You can then get your app_cpu * 100 with:
app_cpu=$((${tmp_cpu%.*} * 100))
Note: Including defunct and ${0##*/} in grep -v prevents against multiple processes matching $app_name.
I use top to check some details. It provides a few more details like CPU time.
On Linux this would be:
top -b -n 1 | grep $app_name
On Mac, with its BSD version of top:
top -l 1 | grep $app_name