Shell Programming and Scripting

Hi, I am reading the contents of a file in variables as -

Code:

cat ${var_file_name} | while read COL1 COL2 COL3 COL4 COL5 COL6 COL7 COL8 COL9 COL10 COL11

The problem is ... my file can have any number of columns - 5, 10, 11 ....
So i want a dynamic variable list as -

Code:

cat ${var_file_name} | while read ${col_expr_list}

where ${col_expr_list} stores the expression like - "COL1 COL2 COL3 COL4 COL5 COL6 COL7 COL8 COL9 COL10 COL11" or "COL1 COL2 COL3 COL4 COL5" depending on the number of column in {var_file_name}

But AIX is throwing an error, when i run the script as "can not find the identifier"

Could anyone please suggest for this.....

Moderator's Comments:

Use code tags please.

Can you get your values/fields in the input file delimeted like a csv file?

yes.. they are already delimited with ':' .... and that's why i am able to populate the COL1 ... COL11 with file values.

But a variable number of fields means that they are empty values in between :: like:

Code:

val1:val2:val3:val4
val1:val2::val4
val1:val2:val3:
:val2:val3:val4

Or is it like

Code:

val1:val2:val3:val4
val1:val2:val4
val1:val2:val3
val2:val3:val4

?

Because in the 1st case this would be no problem to read in. You'd just have empty variables while reading in, like in the infile. Second file would not be good to parse at all imho.

say file A is having 4 fields .. so data in it would be like -
1:2:3:4
11:22:33:44
..
...
so my variable {col_expr_list} would be having - "COL1 COL2 COL3 COL4" .. and the read statement would be -

cat ${var_file_name} | while read {col_expr_list}
do
<some calculations on COL1 to COL4>
done

now say a new file B comes with 6 fields, with data as -
1:2:3:4:5:6

so my variable {col_expr_list} would be having - "COL1 COL2 COL3 COL4 COL5 COL6" .. and the output after "cat" statement should be -
COL1 = 1
COL2 = 2
COL3 = 3
COL4 = 4
COL5 = 5
COL6 = 6

but its not behaving like this .. and throwing error ...

Use arrays

Code:

#!/bin/bash
IFS=':'
ROW=1
while read -a A
do
   echo "Row $ROW"
   for ((i=0; i<${#A[@]}; i++))
   do
      echo -ne "Col$i=${A[$i]}\t"
   done
   echo
   ((ROW++))
done < file

You can adapt this code for your own calculations
the ROW variable is just for displaying purpose.

Thanks Frans .
I will try this and let you know