# How to test for text file **URL:** \ **Category:** ruby-talk\ **Created:** [17 April 2003 03:58 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677 "2003-04-17T03:58:40Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Peter\_B\_Ensch1](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@Peter\_B\_Ensch1](https://rubytalk.org/u/Peter_B_Ensch1)\ **Post date:** [17 April 2003 03:58 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677/1 "2003-04-17T03:58:40Z")
In perl, -T returns true if is a text file and -B returns true if is binary. How do you do this in ruby? I’ve checked File, FileTest, and File.Stat - nothing there to test for text vs. binary filetype. Thanks, P > **···** > > – > ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^^~^~^~^~^ > Peter B. Ensch [peterbe@attbi.com](mailto:peterbe@attbi.com) > ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^^~^~^~^~^ ---
**Author:** ![Yukihiro\_Matsumoto2](https://avatars.discourse-cdn.com/v4/letter/y/b9e5f3/32.png) [@Yukihiro\_Matsumoto2](https://rubytalk.org/u/Yukihiro_Matsumoto2)\ **Post date:** [17 April 2003 05:08 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677/2 "2003-04-17T05:08:53Z")
Hi, > **···** > > In message “How to test for text file” on 03/04/17, “Peter B. Ensch” [pNOeterSPAM4MEbe@attbi.com](mailto:pNOeterSPAM4MEbe@attbi.com) writes: > > > In perl, -T returns true if is a text file and > > -B returns true if is binary. > > You have to define what is text file first. Traditional Perl test > does not work for Japanese text (nor Unicode text). > > ``` > matz. > > ``` ---
**Author:** ![Peter\_B\_Ensch1](https://avatars.discourse-cdn.com/v4/letter/p/cab0a1/32.png) [@Peter\_B\_Ensch1](https://rubytalk.org/u/Peter_B_Ensch1)\ **Post date:** [18 April 2003 16:14 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677/3 "2003-04-18T16:14:08Z")
Yukihiro Matsumoto wrote: > Hi, > > > In perl, -T returns true if is a text file and > > -B returns true if is binary. > > You have to define what is text file first. Traditional Perl test > does not work for Japanese text (nor Unicode text). > > matz. Ah! Not having worked with Unicode before, I had not considered this. Does your answer assume that I need to define ‘text file’ and then open/read the file to see if it meets the definition? In other words, it is not possible to do something like: if text file open and process else do not open end BTW, thanks for answering my question, Matz, and thanks for ruby. I’m having a lot of fun learning it. P > **···** > > > In message “How to test for text file” \> on 03/04/17, “Peter B. Ensch” [pNOeterSPAM4MEbe@attbi.com](mailto:pNOeterSPAM4MEbe@attbi.com) writes: > > – > ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^^~^~^~^~^ > Peter B. Ensch [peterbe@attbi.com](mailto:peterbe@attbi.com) > ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^^~^~^~^~^ ---
**Author:** ![Aredridel1](https://avatars.discourse-cdn.com/v4/letter/a/d07c76/32.png) [@Aredridel1](https://rubytalk.org/u/Aredridel1)\ **Post date:** [18 April 2003 16:30 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677/4 "2003-04-18T16:30:14Z")
Peter B. Ensch wrote: > Ah! Not having worked with Unicode before, I had not considered this. > Does your answer assume that I need to define ‘text file’ and then > open/read the file to see if it meets the definition? In other words, > it is not possible to do something like: > if text file > open and process > else > do not open > end That’s what perl does as well, internally – it opens and checks the (I believe) first line for characters that indicate one way or the other (NUL is a good indication of binary, CRLF is a good indication it’s text, under Windows. Under Unix, and dealing with other character sets, things get way hairier) I’ve never found a good way to detect file types easily – there’s the “file” command under many unices that looks in a database of magic numbers to guess file formats – GIF files start with GIF8?a, where ? is 7 or 9. JPEG files start with JFIF, windows executables with MZ and linux and many other unices use ELF. Windows NT and later stamp unicode text files with an “ordering sequence”, I can’t remember which, but if it’s interpreted with the bytes swapped, it’s invalid unicode, but if correct, is a two byte “NUL” sequence, telling windows which byte order the file is in. If the file command doesn’t see anything that indicates a certain type, it just guesses similarly to perl and says “Binary data” or “text file”. Windows and DOS try to solve this with file extensions, of course, and Macs with creator codes, and nowadays, being unix-based, it’s starting to use some combination of MacOS magic and file extensions and guessing, which starts to get confusing. Unix traditionally avoids the issue by making the user decide what to open, or just throwing errors when it gets an ugly file, like a word processor opening a jpeg. Such fun. Aredridel ---
**Author:** ![Austin\_Ziegler2](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@Austin\_Ziegler2](https://rubytalk.org/u/Austin_Ziegler2)\ **Post date:** [19 April 2003 02:16 UTC](https://rubytalk.org/t/how-to-test-for-text-file/5677/5 "2003-04-19T02:16:30Z")
You could use MIME::Types [RAA:mime-types], which does a decent job of MIME Content-Type analysis, and it knows most extensions for filee types. I may port File::MMagic from Perl to do this sort of thing, though. -austin – Austin Ziegler, austin@halostatue.ca on 2003.04.18 at 22:09:30 > **···** > > On Sat, 19 Apr 2003 01:14:08 +0900, Peter B. Ensch wrote: > > > Yukihiro Matsumoto wrote: > > > > > > In perl, -T returns true if is a text file and -B > > > > returns true if is binary. > > > > You have to define what is text file first. Traditional Perl test > > > > does not work for Japanese text (nor Unicode text). > > > > Ah! Not having worked with Unicode before, I had not considered > > > > this. Does your answer assume that I need to define ‘text file’ > > > > and then open/read the file to see if it meets the definition? In > > > > other words, it is not possible to do something like: > > > > if text file > > open and process > > else > > do not open > > end > > > > BTW, thanks for answering my question, Matz, and thanks for ruby. > > I’m having a lot of fun learning it.