Bash script to perl script

acrobat118 has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks, I am a totally new on perl. I am trying to get data from files with some modifications. I am using the following bash script for each individual *log file.

grep "R35LD1A" HF_UHF_02.50_plot.log | awk '($2**2 <0.00001&&$3**2.<0.
+0001){print $4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17,$18,$19
+,$20,$21,$22,$23,$24,$25,$26,$27,$28,$29,$30,
 $31,$32,$33,$34,$35,$36,$37,$38,$39,$40}' |sort -g -k1 >HF_UHF_02.50_
+plot.res
[download]

Since there are a lot of files so it is hard to do manually using bash for each file. I was trying to write a perl script but I dont know how to modify the above bash script to perl. Please help me. I shall be thankful.

Comment on Bash script to perl script Download Code

Replies are listed 'Best First'.
Re: Bash script to perl script by haukex (Archbishop) on Jun 18, 2016 at 11:15 UTC
Hi acrobat118, Here's a rough outline of what you'll need: Read a file and loop over its lines: "Files and I/O" in perlintro (also covers how to write to an output file) Act only on lines that match a pattern (grep): "Regular expressions" in perlintro Break a line into columns (awk): split, e.g. `my @F = split;` splits the current line `$_` on whitespace; the first column is then `$F[0]`, second column `$F[1]`, etc. Operate only on lines that match certain conditions (awk): "Conditional and looping constructs" in perlintro and the section following it "Builtin operators and functions" Adding the resulting items to an array: push (for a more advanced approach see "arrays of arrays" in perldsc) Sorting the array: sort and "How do I sort an array by (anything)?" in perlfaq4 Try using this information to write some code, and if you run into trouble feel free to ask here. Hope this helps, -- Hauke D Update: Expanded post slightly.	[reply] [d/l] [select]
Re: Bash script to perl script by hippo (Archbishop) on Jun 18, 2016 at 12:19 UTC
Since there are a lot of files so it is hard to do manually using bash for each file. Bash answer: use a loop. Perl has a steep learning curve, and I encourage you to follow the references in the other replies. Perl is much, much more flexible powerful and efficient than bash (or any other shell) in most circumstances and the time spent learning it will pay huge dividends. But, if you just want a quick solution you can look to use the tools with which you are already familiar. One other top tip: never* pipe grep into awk, it's a waste of a process. Instead of your grep above you can do `awk '/R35LD1A/ && ($22 <0.00001&&$32.<0.0001){ ...` [download] *Well, almost never. There are exceptions to every rule after all.	[reply] [d/l]
Re: Bash script to perl script by stevieb (Canon) on Jun 18, 2016 at 11:01 UTC
Well, we'd need to see a chunk of the input file, and an example of what your expected output looks like. Put both of those in `<code></code>` tags like you've put your Bash code in. Also, no matter what it looks like, please show the Perl code that you've made an attempt with, so the Monks can see that you have made at least an attempt.	[reply] [d/l]
Re: Bash script to perl script by ww (Archbishop) on Jun 18, 2016 at 11:04 UTC
Start by studying "Learning Perl" ( Rent The Llama at O'Reilly); the Monastery's Tutorials; and/or any number of on-line college level courses. Then come back with questions about those constructs on which you get stuck: questions including code, some small snippet of data, and exact error/warning messages. Why? because this is a spot to learn; not (free) code-a-matic! Sorry, we expect SOPW to seek wisdom, not to ask us to do so for them.	[reply]
Re: Bash script to perl script by RonW (Parson) on Jun 24, 2016 at 23:50 UTC
There is a2p that can convert most AWK scripts into Perl code. If you do as Hippo suggested, incorporating your grep pattern into AWK: `awk '/R35LD1A/ && ($22 <0.00001&&$32.<0.0001){ ...` then a2p will include that in the Perl code it generates.	[reply] [d/l]