Shell Programming and Scripting

Dear all,

I have a rather large file of numbers which i would like to read into a script and then do some maths on a specific column( e.g column).
so far i have been using the following awk command

Code:

awk '{print $4}' infile.txt > out.tmp

to strip out the desired column within the in perl script and at the end of the script i delete the tmp file, however this is rather cumbersome when dealing with multiple files, does any one have any suggestion how i can do this directly in perl?


Regards




Mish

Code:

while ($line = <STDIN>)
{
    @fields=split /\s+/, $line;
    print $fields[3];
}

in case you don't want to store data from all the columns (you say the file is large, so you won't intend to fill all the memory):

Code:

# get_fourth.pl
@fourth_column;
while ($line = <>) {
    push (@fourth_column, (split(/\s+/, $line))[3]);
}
print join(' ', @fourth_column);

Code:

$ perl get_fourth.pl datafile

Use the -F flag so you can have the file automatically split into an array.

Example (Printing the second column of a tab-delimited file):

Code:

 cat temp.txt | perl -F"\t" -ane 'print $F[1] . "\n"'