How to parse FASTQ file?

[Shishir]

I am new in NGS. I need to format some fastq files. For example I want to replace characters /1 and /2 with -1 and - 2 in the files having data like @HWUSI-EAS1671_0001:5:1:1022:10290/1.
I tried to do it in perl with pattern matching but the files are too big to parse. Could anyone please give me suggestion on share any code?

[GenoMax]

Have you considered using "awk"?

[Shishir]

Thanks!
I searched for "awk" and realize "sed" can do it easily

[kopi-o]

The files are surely not too big to parse with perl (for your purposes) if you do it right - you only need to have four lines at a time (or maybe just one) in memory. Also it might be a good opportunity to learn some BioPerl :-)