Determining a file format 2350

Silvio Rocco

First, you need to determine what you are talking about. ANSI is the American National Standards Insbreastute. It changes name frequently, and I do not know what it is currently called. They should have a standard for their name.

Second, ASCII is the American Standard Code for Information Interchange. This is a 7-bit code (allowing for the 8-th bit, if present, to be used for parity checking: important when punched paper tape was used). It is normally used only for text-only documents in English, though it can be used for similar languages.

Third, file(1) works as well as I might expect:

M&C business forward Dec 2005.doc: Microsoft Office Document 000920.xls.as: Applixware Spreadsheet 119970.pdf: PDF document, version 1.4 119971.pdf: PDF document, version 1.4 19881028TechB.xls: Microsoft Office Document 2.4.21-40.ELhugemem.iso: ISO 9660 CD-ROM filesystem data 20042005SMMBudget.as: Applixware Spreadsheet 20042005SMMBudget.as.pdf: PDF document, version 1.2 20042005SMMBudget.as.ps: PostScript document text conforming at level 3.0 20042006SMMBudget.as: Applixware Spreadsheet 20042006SMMBudget.tsv: ASCII text 2004veri.p12: data 20051219NuNu.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, 1 x 1 20060224PandSagenda.rtf.aw: Applixware Words Document 20060731BS.tsv: ASCII text 20060732CM.tsv: ASCII text 20060732YTD.tsv: ASCII text 20061731TTM.tsv: ASCII text 2sidedPrint.asp: ASCII English text, with very long lines, with CRLF line terminators 364.pdf: PDF document, version 1.3 AFCPSpLCHotTopicsEurospeech03final.pdf: PDF document, version 1.3 APCASTE-5T3TSZR1EN.pdf: PDF document, version 1.3 APCFLUU-5T3TLTR1EN.pdf: PDF document, version 1.3 APCSADE-5TNM3YR4EN.pdf: PDF document, version 1.2 ARRL: directory ATI5266.pdf: PDF document, version 1.6 ATT06158.htm: exported SGML document text AlexandraGoodnough.abw: XML document text

I do not know just how file(1) works, but I imagine it examines the first few bites for characteristic signature information (e.g., "magic numbers"). It almost certainly does not look at "suffixes" because the concept does not really exist in most file systems (e.g., UNIX, linux, etc.) and can easily be forged anyway.

When file(1) fails, you are pretty much on your own.

-- .~. Jean-David Beyer Registered Linux User 85642. V PGP-Key: 9A2FC99A Registered Machine 241939. ^^-^^ 10:20:01 up 9 days, 19:28, 3 users, load average: 4.41, 4.37, 4.29