Thread: Newbie Bash scripting issues

hi all,

extremely unexperienced in writing in bash , not experienced coding @ all, have no issue learning.

trying implement mail alert when of gpu temperature sensors go below centigrade. plan on using cron job runs every 10-15 minutes or , sends mail through exim , smarthost if pre-mentioned conditions met.

below bash script have far:

code:

#!/bin/bash min="80" temp0= display=:0 aticonfig --odgt --adapter=0 | sed -n '/[0-9][0-9]\.[0-9][0-9]/,$p' | sed 's/.*\([0-9][0-9]\)\..*/\1/' temp1= display=:0 aticonfig --odgt --adapter=1 | sed -n '/[0-9][0-9]\.[0-9][0-9]/,$p' | sed 's/.*\([0-9][0-9]\)\..*/\1/' temp2= display=:0 aticonfig --odgt --adapter=2 | sed -n '/[0-9][0-9]\.[0-9][0-9]/,$p' | sed 's/.*\([0-9][0-9]\)\..*/\1/' temp3= display=:0 aticonfig --odgt --adapter=3 | sed -n '/[0-9][0-9]\.[0-9][0-9]/,$p' | sed 's/.*\([0-9][0-9]\)\..*/\1/' echo $temp0 echo $temp1 echo $temp2 echo $temp3 echo $min if [ "$temp0" -lt "$min" ];         echo "something not right..." else         echo "everything looks ok" fi

everything below line 6 testing variables grabbed correctly , whether condition working.

condition plan on using 4 temperature's being checked against $min using || operator.

when run script following:

code:

76 74 70 74     80 tempcheck.sh: line 12: [: : integer expression expected looks ok

now, expect if statement executed, rather else statement. assuming else statement being triggered because there sort of error in comparison can't work out.

reference, here output display=:0 aticonfig cmd before sed gets it:

code:

  :~# display=:0 aticonfig --odgt --adapter=0  adapter 0 - ati radeon hd 5800 series             sensor 0: temperature - 76.00 c

any appreciated.

jg

edit: realise how messy sed / regex , appreciate if me clean up, again.

you don't capture output if sees null value
notice 4 empty lines in output, that's echo $temp0 ... echo $temp3 sequence. can see variables empty

code:

temp0=$( display=:0 aticonfig --odgt --adapter=0 .... )

if sure there 1 occurence of [0-9]{2}.[0-9]{2} can use grep -o returns matching part (76.00), simplify next part fraction part dropped.

code:

echo $'test 6.66\ntest 76.00\ntest 112.99' test 6.66 test 76.00 test 112.99  echo $'test 6.66\ntest 76.00\ntest 112.99' | grep -oe '[0-9]{2,3}[.][0-9]{2}' | sed -r 's/([0-9]*).*/\1/g' 76 112

note used {2,3} allow numbers above 100
sed -r allows dropping painful escaping thing of dots, parentheses , stuff assumes have regex meaning.

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