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Arithmetic (number-based) if condition

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# 1  
Old 03-27-2012
Arithmetic (number-based) if condition
Hi Folks

I'm looking for help with if statement.

I'm reading the file with header (starts with 0 on position 1 in the line) and data (starts with 1 on position 1 in the line).
I have to check if the number from header (should be number of data rows) equal actual count of the data rows.

When both equal than extrsct specific data and write sql statement into the file that will be further processed.

File is as follows:

Quote:
07
1ABC123456000COIN12345
1ABC123466000COIN12345
1ABC123476000COIN12345
1ABC123486000COIN12345
1ABC123496000COIN12345
1ABC123506000COIN12345
1LST123516000COIN12345
Script as follows

Code:
input_file="file.txt"
output_file="Query.sql"
table_name="file_history"

row_header=`head -1 $input_file | cut -c2-10`
row_count=`grep -c "^1" $input_file`

make_file()
{
echo "INSERT ALL"
grep "^1" $input_file | cut -c2-10 | while IFS= read;do printf "Into %s values ('%s',SYSTIMESTAMP) \n" $table_name "$REPLY";done
echo "SELECT * FROM dual;"
}

if [ $row_count -eq $row_header ]; then
{
grep "^1" $input_file | cut -c2-10 | while read line; do 
    echo $line
done
make_file > $output_file
echo "File has $row_count data rows"
}

elif [[ -e $output_file ]]; then
{
echo "Data corrupt. Incorrect number of rows in the file. Query file deleted"
rm $output_file
}

else
echo "Data corrupt. Incorrect number of rows in the file. Query file do not exist"

fi

When I run the script I'm getting following error

Quote:
: integer expression expected
Data corrupt. Incorrect number of rows in the file. Query file do not exist
however it should equal as:
row_header=`head -1 $input_file | cut -c2-10` is 7
row_count=`grep -c "^1" $input_file` is also 7.

When I change code to
Code:
if [ $row_count -eq 7 ]; then

than it is working fine but I can't hardcode this variable.

Thanks for help
# 2  
Old 03-27-2012
This will take an input file and only print those data blocks that meet the criteria you defined. Run against this file with one good block and two bad ones:
Code:
07
1ABC123456000COIN12345
1ABC123466000COIN12345
1ABC123476000COIN12345
1ABC123486000COIN12345
1ABC123496000COIN12345
1ABC123506000COIN12345
1LST123516000COIN12345
07
1ABC123466000COIN12345
1ABC123476000COIN12345
1ABC123486000COIN12345
1ABC123496000COIN12345
1ABC123506000COIN12345
1LST123516000COIN12345
05
1ABC123456000COIN12345
1ABC123466000COIN12345
1ABC123476000COIN12345
1ABC123486000COIN12345
1ABC123496000COIN12345
1ABC123506000COIN12345
1LST123516000COIN12345

gives
Code:
07
1ABC123456000COIN12345
1ABC123466000COIN12345
1ABC123476000COIN12345
1ABC123486000COIN12345
1ABC123496000COIN12345
1ABC123506000COIN12345
1LST123516000COIN12345

Code:
awk ' /^0/ { if(start && start==lcount){ printf("%02d\n%s", start,lines)}
             start=$0
             lines=""
             lcount=0
           } 
     /^1/ {lcount++; lines=lines sprintf("%s\n",$0) }
     END {if (start==lcount ){ printf("%02d\n%s", start,lines) }} ' filename

# 3  
Old 03-27-2012
Your data file is in DOS format (ie ^M on the end of lines). Try running it thru dos2unix first.

Or do it all with awk:

Code:
awk -v table=file_history -v outfile=Query.sql '
  /^0/ {c=substr($0,2) }
  /^1/ {L[g++]=substr($0,2)}
  END{
    if(g!=c)
        print "Data corrupt. Incorrect number of rows in the file"
    else {
      print "INSERT ALL" > outfile
      for(i=0;i<g;i++)
        printf "Into %s values (%c%s%c, SYSTIMESTAMP)\n",table,39,L[i],39 >> outfile
      print "SELECT * from dual;" >> outfile
  }}' file.txt

Last edited by Chubler_XL; 03-27-2012 at 11:52 PM..
# 4  
Old 03-28-2012
Thank you both.

dos2unix seems to resolve my initial issue, however both of you suggested to use awk.

I tested scripts and both work fine.

Is there any advantage to use awk rather then other commands?
# 5  
Old 03-28-2012
awk offers a slight performance improvement, as each time the shell executes an external command like head, grep, cut and with some shell/OS printf, the program code must be loaded from disk and a new process forked to execute it, this consumes resources. Also in your current solution, the data file is being opened a read in at least four times by various commands, so there is some wasted effort there.

However, if the data file isn't overly large and the script isn't executed frequently there is no real issue. What is much more important is that you understand how your script works and can easily support/change it in the future.

It looks like you have a pretty good grip on shell programming so I doubt your going to find awk confusing or difficult and I'm sure if you start using it regularly you quickly grow to love it.
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