linux - BASH shell script works properly at command prompt but doesn't work with crontab -

here script want execute crontab.

#!/bin/bash # file of path /home/ksl7922/memory_test/run_process.sh # 'mlp' name of process, , 'ksl7922' user account.  prgep mlp > /home/ksl7922/proc.txt  # line give number of process of 'mlp' result=`sed -n '$=' /home/ksl7922/proc.txt` echo "result = ${result}"  # if 'mlp' processes run less six, read text file 1 line , delete  # it, , execute line.  if ((result < 6));     filename="/home/ksl7922/memory_test/task_reserved.txt"     cat $filename | while read line              # delete line first.         sed -i "$line/d" $filename          # execute line         eval $line          break;     done else     echo "you're doing great." fi 

after that, editted crontab , checked crontab -l

*/20 * * * * sh /home/ksl7922/memory_test/run_process.sh 

this scripts works command line, however, doesn't work crontab.

it seems shell script works crontab anyway, because 'proc.txt' file generated, , first line of 'task_reserved.txt' removed.

however, didn't see messages, , result file of 'mlp' processes.

since i'm not @ english, i'm afraid guys don't understand intention. anyway, can let me know how handle this?

1. my bet path environment variable not correctly set within cron. insert

   echo $path > /tmp/cron-path.txt 

   to see value has. perhaps need manually set proper value within script.

   this faq

   • https://askubuntu.com/questions/23009/reasons-why-crontab-does-not-work
   • https://askubuntu.com/questions/117978/script-doesnt-run-via-crontab-but-works-fine-standalone

2. if don't have mail installations on system cron forward error messages script, it's practice manually redirect error messages preferred location. eg.

   #! /bin/bash {     date      prgep mlp > /home/ksl7922/proc.txt     ... snip ...     fi } &> /tmp/cron-msg.txt