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Read numbers from file

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# 1  
Old 05-10-2013
Read numbers from file
I am trying to make a script to read marks from a file then find out how many of them are above 40 (passing marks). However my script is getting stuck at "read num". I dont understand whats the problem. Any help will be much appreciated.

Code:
#!/bin/bash
set -x
count=0; countP=0;  PASSMK=40
max=-1;  min=999999
tot=0;   avg=0
read num #read the first input number
while [ $num -ge 0 ]; do
  tot=$(($tot+$num))
  if [ $num -gt $max ]; then
    max=$num
  fi
  if [ $num -lt $min ]; then
    min=$num
  fi

  count=$(($count+1))
  if [ $num -ge $PASSMK ]; then
    countP=$(($countP+1));
  fi

  read num #read the next input number
done

if [ $count -gt 0 ]; then
  avg=$(($tot/$count))
fi
printf "entries\tpasses\tmax\tmin\tavg\n"
printf "%d\t%d\t%d\t%d\t%d\n" "$count" "$countP" "$max" "$min" "$avg"

Last edited by vish6251; 05-10-2013 at 06:59 AM..
# 2  
Old 05-10-2013
Quote:
Originally Posted by vish6251
I am trying to make a script to read marks from a file then find out how many of them are above 40 (passing marks). However my script is getting stuck at "read num". I dont understand whats the problem. Any help will be much appreciated.

Code:
#!/bin/bash
set -x
count=0; countP=0;  PASSMK=40
max=-1;  min=999999
tot=0;   avg=0

read num #read the first input number
while [ $num -ge 0 ]; do
  tot=$(($tot+$num))
  if [ $num -gt $max ]; then
    max=$num
  fi
  if [ $num -lt $min ]; then
    min=$num
  fi

  count=$(($count+1))
  if [ $num -ge $PASSMK ]; then
    countP=$(($countP+1));
  fi

  read num #read the next input number
done

if [ $count -gt 0 ]; then
  avg=$(($tot/$count))
fi
printf "entries\tpasses\tmax\tmin\tavg\n"
printf "%d\t%d\t%d\t%d\t%d\n" "$count" "$countP" "$max" "$min" "$avg"

You said you want the read commands to read from a file, but you haven't specified any file. Therefore, both read commands will read from the standard input for your bash script. In other words, the script is waiting for you to type in values to be processed.

If you want to choose a different file each time you run the script, you can redirect the input of your script when you run it, as in:
Code:
script_name < input_file

If you always want the read command in your script to read from the same file every time you run the script, change the line marked in red in your script above with:
Code:
done < input_file

This User Gave Thanks to Don Cragun For This Post:
vish6251
# 3  
Old 05-10-2013
Quote:
Originally Posted by Don Cragun
You said you want the read commands to read from a file, but you haven't specified any file. Therefore, both read commands will read from the standard input for your bash script. In other words, the script is waiting for you to type in values to be processed.

If you want to choose a different file each time you run the script, you can redirect the input of your script when you run it, as in:
Code:
script_name < input_file

If you always want the read command in your script to read from the same file every time you run the script, change the line marked in red in your script above with:
Code:
done < input_file

I knew i had to specify a file, then i tried adding "num=$1" that didn't work. But your suggestion worked perfectly! thank you!
# 4  
Old 05-10-2013
You better do
Code:
while read num #read an input number
do
 if [ $num -ge 0 ]; then
  ... #without a further read
 fi
done

Eventually done < input_file
This User Gave Thanks to MadeInGermany For This Post:
vish6251
# 5  
Old 05-10-2013
The previous suggestion worked for me however, now instead of a txt file with one integer per line, I want read a csv file and apply script to get the statistics of marks. How would i extract values from column 3 of csv file and feed them to the script? can i use 'awk' ?
Sample csv :
Code:
12;28;32;32
23;54;75;6
12;34;55;45
242;42;85;63
32;4;24;38
-1;-1;-1;-1

Last edited by vish6251; 05-10-2013 at 10:40 AM..
# 6  
Old 05-10-2013
I see you have a semicolon separated file. In that case specify IFS (Internal Field Separator) as semicolon and read:
Code:
while IFS=";" read f1 f2 f3 f4
do
        printf "%d\n" $f3
done < input_file

# 7  
Old 05-10-2013
Quote:
Originally Posted by Yoda
I see you have a semicolon separated file. In that case specify IFS (Internal Field Separator) as semicolon and read:
Code:
while IFS=";" read f1 f2 f3 f4
do
        printf "%d\n" $f3
done < input_file

Please check my script. How can i supply values of $f3 to $num?
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