# IO.pos bug? **URL:** \ **Category:** Ruby\ **Created:** [July 28, 2008, 8:35pm UTC](https://www.ruby-forum.com/t/io-pos-bug/144341 "2008-07-28T20:35:48Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 28, 2008, 8:35pm UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/1 "2008-07-28T20:35:48Z")
irb(main):001:0\> f = File.new("/etc/host.conf") =\> #\ irb(main):002:0\> f.gets =\> “multi off\n” irb(main):003:0\> f.pos =\> 10 irb(main):004:0\> f.gets =\> “order hosts,bind\n” irb(main):005:0\> f.pos =\> 27 irb(main):006:0\> f.close =\> nil All right. irb(main):007:0\> f = File.new("/etc/host.conf") =\> #\ irb(main):008:0\> f.sysread(5) =\> “multi” irb(main):009:0\> f.pos =\> 5 irb(main):010:0\> f.sysread(10) =\> " off\norder" irb(main):011:0\> f.pos =\> 5 Bug? % ruby1.8 --version ruby 1.8.5 (2006-08-25) [i486-linux] ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 28, 2008, 8:39pm UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/2 "2008-07-28T20:39:20Z")
Hi – On Tue, 29 Jul 2008, andrey wrote: > irb(main):006:0\> f.close > irb(main):010:0\> f.sysread(10) > =\> " off\norder" > irb(main):011:0\> f.pos > =\> 5 > > Bug? > % ruby1.8 --version > ruby 1.8.5 (2006-08-25) [i486-linux] It works OK in 1.8.6: irb(main):001:0\> f = File.new("/etc/hosts") =\> #\ irb(main):002:0\> f.sysread(5) =\> "##\n# " irb(main):003:0\> f.pos =\> 5 irb(main):004:0\> f.sysread(10) =\> “Host Datab” irb(main):005:0\> f.pos =\> 15 I don’t think 1.8.5 is supported any more, so it might be good to update your installation if possible. David ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 30, 2008, 2:09am UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/3 "2008-07-30T02:09:04Z")
On Mon, Jul 28, 2008 at 8:38 PM, David A. Black [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > irb(main):004:0\> f.gets > > irb(main):008:0\> f.sysread(5) > > ruby 1.8.5 (2006-08-25) [i486-linux] > > It works OK in 1.8.6: […] > I don’t think 1.8.5 is supported any more, so it might be good to > update your installation if possible. > > David It works for me with 1.8.5 too: irb(main):007:0\> f = File.new(“/tmp/jhjh”) =\> #\ irb(main):008:0\> f.sysread(5) =\> “multi” irb(main):009:0\> f.pos =\> 5 irb(main):010:0\> f.sysread(10) =\> " off\norder" irb(main):011:0\> f.pos =\> 15 $ ruby -v ruby 1.8.5 (2006-08-25) [powerpc-darwin8.8.0] I have built this “ruby” myself from source (but note that it is on Mac OS X, not Linux). /Johan H. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 30, 2008, 8:29pm UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/4 "2008-07-30T20:29:17Z")
Same here…on ruby 1.8.7 (2008-06-20 patchlevel 22) [i686-linux] Regards, John. irb(main):001:0\> f = File.new("/etc/hosts") =\> #\ irb(main):002:0\> f.sysread(5) =\> “#\n# /” irb(main):003:0\> f.pos =\> 5 irb(main):004:0\> f.sysread(10) =\> “etc/hosts:” irb(main):005:0\> f.pos =\> 5 irb(main):006:0\> ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 31, 2008, 3:33am UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/5 "2008-07-31T03:33:30Z")
From: John Slobbe [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] # Same here…on ruby 1.8.7 (2008-06-20 patchlevel 22) [i686-linux] # irb(main):001:0\> f = File.new(“/etc/hosts”) # =\> #\ # irb(main):002:0\> f.sysread(5) # =\> “#\n# /” # irb(main):003:0\> f.pos # =\> 5 # irb(main):004:0\> f.sysread(10) # =\> “etc/hosts:” # irb(main):005:0\> f.pos # =\> 5 i seem to remember (don’t know where/when) that you must not mix low level calls like #sysread w highlevel calls like #pos, use #read with #pos, or use #sysread w #sysseek but i guess we need a confirmation fr the core dev to verify that. Nobu perhaps? eg, irb(main):016:0\> File.open “/etc/hosts” do |f| irb(main):017:1\* f.sysread 2 irb(main):018:1\> p f.sysseek(0,IO::SEEK\_CUR) irb(main):019:1\> f.sysread 10 irb(main):020:1\> p f.sysseek(0,IO::SEEK\_CUR) irb(main):021:1\> end 2 12 =\> nil irb(main):022:0\> RUBY\_VERSION =\> “1.8.7” hth. kind regards -botp ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [July 31, 2008, 9:27am UTC](https://www.ruby-forum.com/t/io-pos-bug/144341/6 "2008-07-31T09:27:56Z")
Hi, At Thu, 31 Jul 2008 10:31:24 +0900, Peña, Botp [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote in [ruby-talk:309630]: > i seem to remember (don’t know where/when) that you must not > mix low level calls like #sysread w highlevel calls like > #pos, use #read with #pos, or use #sysread w #sysseek > > but i guess we need a confirmation fr the core dev to verify > that. Nobu perhaps? You’re correct, it depends on underlying libc, since 1.8 uses stdio. 1.9 has its own buffering mechanism and doesn’t have that issue.