# Problem with 2nd File.Read in small script

**URL:** <https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018>\
**Category:** Ruby\
**Created:** [May 9, 2006, 2:59pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018 "2006-05-09T14:59:56Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 9, 2006, 2:59pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/1 "2006-05-09T14:59:56Z")

</div>

Hello,  
Can someone look at my code below? I have a RUBY debugger that indicates  
to me that when I get to the 2nd “File.read” below, all of the previous  
variables are wiped away. I’d like to know why that is. I need to do 2  
searches, 2 scans, in the same files. It doesn’t seem to like my 2nd  
pass. As a result, nothing past my 2nd File.read occurs.

Thank you.

* * *

require ‘FileUtils’  
Dir.chdir(“c:/scripts/ruby/temp”)  
psfiles = Dir.glob(’\*.ps’)

blankpages = []

psfiles.each do |psfile|  
infofile = File.basename(psfile, ‘.ps’)  
File.open(psfile, “a”) do |writepage|  
File.read(psfile).scan(/%%Pages: (\d{1,5})\n/) do  
totalnumberofpages = $1  
#If the page count is odd, then, add a blank to make it an even  
page count.  
if (totalnumberofpages.to\_i % 2) !=0 then  
writepage \<\< “%%Blank page from Asura\nshowpage\n”  
blankpages = totalnumberofpages.to\_i + 1.to\_i  
end  
end

File.read(psfile).scan(/%%Page: [(\d)()]+  
(\d{1,5})\n%%PageBoundingBox:  
\d{1,5} \d{1,5} \d{1,5} \d{1,5}\n%%PageOrientation:/) do  
blankpages.push($1)  
File.open(infofile + “.pageinfo”, “w”) do |writetext|  
writetext \<\< “Number of blankpages in this PDF:  
#{blankpages.length}\n” \<\<  
“Blank Pages in This PDF: #{blankpages.join(’ ')}\n”  
end  
end  
end  
end

---

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 9, 2006, 8:08pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/2 "2006-05-09T20:08:39Z")

</div>

Peter B. wrote:

> require ‘FileUtils’  
> #If the page count is odd, then, add a blank to make it an even  
> blankpages.push($1)  
> File.open(infofile + “.pageinfo”, “w”) do |writetext|  
> writetext \<\< “Number of blankpages in this PDF:  
> #{blankpages.length}\n” \<\<  
> “Blank Pages in This PDF: #{blankpages.join(’ ')}\n”  
> end  
> end  
> end  
> end

I think part of the issue here is that you open the file for writing,  
then do a read on the same file. Looking at IO.read:

Opens the file, optionally seeks to the given offset, then returns  
/length/ bytes (defaulting to the rest of the file). read ensures the  
file is closed before returning.

But you have already opened the file. So, your structure above looks  
something like:

File.open(psfile) { #opens psfile

```
File.read(psfile) { #opens psfile

} #closes psfile

File.read(psfile) { #opens psfile

} #closes psfile

```

} #closes psfile

I’m not sure if that is the problem or not.

-Justin

---

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**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 9, 2006, 8:58pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/3 "2006-05-09T20:58:06Z")

</div>

Justin C. wrote:

> Peter B. wrote:
> 
> > require ‘FileUtils’  
> > #If the page count is odd, then, add a blank to make it an even  
> > blankpages.push($1)  
> > File.open(infofile + “.pageinfo”, “w”) do |writetext|  
> > writetext \<\< “Number of blankpages in this PDF:  
> > #{blankpages.length}\n” \<\<  
> > “Blank Pages in This PDF: #{blankpages.join(’ ')}\n”  
> > end  
> > end  
> > end  
> > end
> 
> I think part of the issue here is that you open the file for writing,  
> then do a read on the same file. Looking at IO.read:
> 
> Opens the file, optionally seeks to the given offset, then returns  
> /length/ bytes (defaulting to the rest of the file). read ensures the  
> file is closed before returning.
> 
> But you have already opened the file. So, your structure above looks  
> something like:
> 
> File.open(psfile) { #opens psfile
> 
> ```
> File.read(psfile) { #opens psfile
> 
> } #closes psfile
> 
> File.read(psfile) { #opens psfile
> 
> } #closes psfile
> 
> ```
> 
> } #closes psfile
> 
> I’m not sure if that is the problem or not.
> 
> -Justin

Thanks, Justin. Your comments made me dive deeper, and, it works!  
Obviously, there shouldn’t be any reason why I couldn’t read a file  
twice, or as many times as I needed. But, I did make it neater here,  
closing one read before starting another. . . .

require ‘FileUtils’  
Dir.chdir(“c:/scripts/ruby/temp”)  
psfiles = Dir.glob(’\*.ps’)

blankpages = []  
totalpages = 0

psfiles.each do |psfile|  
infofile = File.basename(psfile, ‘.ps’)  
#Scan for the number of pages in the original PDF.  
File.read(psfile).scan(/%%Pages: (\d{1,5})\n/) do  
File.open(psfile, “a”) do |writepage|  
totalpages = $1  
#totalpages.push($1)  
#If the page count is odd, then, add a blank to make it an even page  
count.  
if (totalpages.to\_i % 2) !=0 then  
writepage \<\< “%%Blank page from Asura\nshowpage\n”  
totalpages = totalpages.to\_i + 1.to\_i  
end  
end  
end  
File.read(psfile).scan(/%%Page: [(\d)()]+  
(\d{1,5})\n%%PageBoundingBox:  
\d{1,5} \d{1,5} \d{1,5} \d{1,5}\n%%PageOrientation:/) do  
blankpages = $1  
end  
File.open(infofile + “.pageinfo”, “w”) do |writetext|  
writetext \<\< “Total number of pages in this PDF: #{totalpages}\n”  
\<\<  
“Number of blank pages in this PDF:   
#{blankpages.length}\n” \<\< “Blank Pages\ in This PDF:  
#{blankpages.join(’ ')}\n”  
end  
end

---

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 9, 2006, 9:49pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/4 "2006-05-09T21:49:48Z")

</div>

Logan C. wrote:

> On May 9, 2006, at 2:58 PM, Peter B. wrote:
> 
> > > > end  
> > > > file is closed before returning.
> > 
> > blankpages = []  
> > page  
> > blankpages = $1
> > 
> > –  
> > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).
> 
> If you are going to File.read the whole file into memory anyway, I  
> would do it once, make _all_ my modifications on the string and then  
> write the whole string out.
> 
> e.g.
> 
> file\_contents = File.read(psfile)
> 
> file\_contents.scan(%%Pages: (\d{1,5})\n/) do  
> if odd  
> file\_contents \<\< blank\_page  
> end  
> end
> 
> file\_contents.scan(/%%Page: [(\d)()]+  
> (\d{1,5})\n%%PageBoundingBox:  
> \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n%%PageOrientation:/) do  
> …  
> end
> 
> File.open(psfile, “w”) { |f| f.print file\_contents }

Good idea! Thanks, Logan. I’ll try it. I’ve got a pretty healthy box,  
with lots of memory, so, I may as well just do it all in there at once.  
You’re right.

-Peter

---

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 10, 2006, 3:01pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/5 "2006-05-10T15:01:38Z")

</div>

2006/5/9, Peter B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> Logan C. wrote:

> > If you are going to File.read the whole file into memory anyway, I  
> > would do it once, make _all_ my modifications on the string and then  
> > write the whole string out.

> Good idea! Thanks, Logan. I’ll try it. I’ve got a pretty healthy box,  
> with lots of memory, so, I may as well just do it all in there at once.  
> You’re right.

If you cannot do that I guess it’s still more efficient to open the  
file _once_ for reading and writing instead of opening and closing it  
all the time and then do all the operations before closing it again.

14:53:21 [tmp]: echo 1 \> x  
14:53:24 [tmp]: ruby -e ‘File.open(“x”, File::RDWR) {|io| io.seek 0;  
puts io.read; io.seek 0, IO::SEEK\_END; io.puts “foo”}’  
1  
14:54:51 [tmp]: cat x  
1  
foo

HTH

robert

---

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**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [May 9, 2006, 9:11pm UTC](https://www.ruby-forum.com/t/problem-with-2nd-file-read-in-small-script/60018/6 "2006-05-09T21:11:22Z")

</div>

On May 9, 2006, at 2:58 PM, Peter B. wrote:

> > > end  
> > > file is closed before returning.
> 
> blankpages = []  
> page  
> blankpages = $1
> 
> –  
> Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).

If you are going to File.read the whole file into memory anyway, I  
would do it once, make _all_ my modifications on the string and then  
write the whole string out.

e.g.

file\_contents = File.read(psfile)

file\_contents.scan(%%Pages: (\d{1,5})\n/) do  
if odd  
file\_contents \<\< blank\_page  
end  
end

file\_contents.scan(/%%Page: [(\d)()]+  
(\d{1,5})\n%%PageBoundingBox:  
\d{1,5} \d{1,5} \d{1,5} \d{1,5}\n%%PageOrientation:/) do  
…  
end

File.open(psfile, “w”) { |f| f.print file\_contents }