bash - linux script with netcat stops working after x hours -

i've have scripts:

#!/bin/bash  netcat -lk -p 12345 | while read line     match=$(echo $line | grep -c 'keep-alive')     if [ $match -eq 1 ];         [start command]     fi done 

and

#!/bin/bash  netcat -lk -p 12346 | while read line     match=$(echo $line | grep -c 'keep-alive')     if [ $match -eq 1 ];         [start command]     fi done 

i've put 2 scripts in '/etc/init.d/'

when restart linux machine (rasbpi), both scripts work fine.

i've tried them 20 times, , keep working fine.

but after around 12 hours, whole system stops working. i've put in loggin, seems scripts not reacting anymore. when i;

ps aux 

i can see scripts still running:

root      1686  0.0  0.2   2740  1184 ?        s    aug12   0:00 /bin/bash /etc/init.d/script1.sh start root      1689  0.0  0.1   2268   512 ?        s    aug12   0:00 netcat -lk 12345 root      1690  0.0  0.1   2744   784 ?        s    aug12   0:00 /bin/bash /etc/init.d/script1.sh start root      1691  0.0  0.2   2740  1184 ?        s    aug12   0:00 /bin/bash /etc/init.d/script2.sh start root      1694  0.0  0.1   2268   512 ?        s    aug12   0:00 netcat -lk 12346 root      1695  0.0  0.1   2744   784 ?        s    aug12   0:00 /bin/bash /etc/init.d/script2.sh start 

after reboot start working again... thats sin, rebooting linux machine periodically...

i've inserted loggin, here's outcome;

listening on [0.0.0.0] (family 0, port 12345) [2013-08-14 11:55:00] starting loop. [2013-08-14 11:55:00] starting netcat. netcat: address in use [2013-08-14 11:55:00] netcat has stopped or crashed. [2013-08-14 11:49:52] starting loop. [2013-08-14 11:49:52] starting netcat. listening on [0.0.0.0] (family 0, port 12345) connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6333) connection closed, listening again. connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6334) [2013-08-14 12:40:02] starting loop. [2013-08-14 12:40:02] starting netcat. netcat: address in use [2013-08-14 12:40:02] netcat has stopped or crashed. [2013-08-14 12:17:16] starting loop. [2013-08-14 12:17:16] starting netcat. listening on [0.0.0.0] (family 0, port 12345) connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6387) connection closed, listening again. connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6388) [2013-08-14 13:10:08] starting loop. [2013-08-14 13:10:08] starting netcat. netcat: address in use [2013-08-14 13:10:08] netcat has stopped or crashed. [2013-08-14 12:17:16] starting loop. [2013-08-14 12:17:16] starting netcat. listening on [0.0.0.0] (family 0, port 12345) connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6167) connection closed, listening again. connection [16.8.94.19] port 12345 [tcp/*] accepted (family 2, sport 6168) 

thanks

about loop this.

#!/bin/bash  (( ;; ))     netcat -lk -p 12345 | while read line             match=$(echo "$line" | grep -c 'keep-alive')         if [ "$match" -eq 1 ];             [start command]         fi     done     sleep 4s done 

with added double quotes keep safer.

and try capturing errors , add logging format:

#!/bin/bash  {     echo "[$(date "+%f %t")] starting loop."      (( ;; ))             echo "[$(date "+%f %t")] starting netcat."          netcat -lk -p 12345 | while read line                     match=$(echo "$line" | grep -c 'keep-alive')             if [ "$match" -eq 1 ];                 [start command]             fi         done          echo "[$(date "+%f %t")] netcat has stopped or crashed."          sleep 4s     done } >> "/var/log/something.log" 2>&1 

your read command better in format since read lines unmodified:

... | while ifs= read -r line 

some suggest use of process substitution don't recommend time since through | while ... method while loop able run on subshell , keep outer for loop safe in case crashes. besides there isn't variable while loop needed outside of it.

i'm having idea issue might have been related input , how while read line; ...; done block handles and not netcat itself. variables not being quoted around "" 1 of it, or actual reason why netcat crashing.