Read First Character of Each Line in File

Shell Programming and Scripting
1

I need a better way to read the first character of each line in a file and check if it equals the special character �. This character tells me where there is a break in the reports. The file has over 500,000 lines. Currently, this is my code -

if [[ $(echo $line|cut -c1-1) = "�" ]]

I am using Korn Shell as a scripting language. Is there a better way to do this?

Thank you for your assistance.

2

I don't know if it will make much difference, but you can try this:

typeset -L1 mOne
while read mLine
do
  mOne=$mLine
done < input_file
3

Try:

if [ ${line:0:1} = '�' ]
then
  # bingo
fi

Regards

4

${line:0:1}

works in bash just fine, but not ksh.

5

Shell_Life's suggestion helped a lot. Processing time went from over 5 hours to 45 minutes. This was the code:

typeset -L1 mOne
while read mLine
do
mOne=$mLine
done < input_file

jim mcnamara was correct that ${line:0:1} would not work.

Thank you for the help.

6

I apologize, didn't realise that.

Regards

7

what do you want to do after you have checked the first character equals something?

awk  '/^c/{ do something }' file
8

It would work if you use the enhanced korn shell (ksh93). For something that takes this long it might be worth testing to see which is faster, assigning it to a one character variable with typeset in the standard korn shell or using the enhanced korn shell's variable substitution. Of course going from 5 hours to 45 minutes is already a pretty nice improvement. :slight_smile: