Re: searching non plain text files

On Sun, 16 Dec 2018 20:16:08 -0500, John wrote: > On Sun, 2018-12-16 at 14:33 -0500, Tedd Sperling wrote: >> > On Dec 14, 2018, at 11:19 PM, Jeffry Killen <jekillen@prodigy.net> wrote: >> > >> > >> > Can anyone point me to instruction/advice about >> > opening and reading files that are not plain text: >> >> Jeffry: >> >> I don’t know if this will help you, but most “honest” files have a header that >> states what it is. >> >> Try using a hex-editor app and observing the first 10 characters in their >> headers (i.e., start of the file). For example, a PDF file will state ‘PDF’, a >> jpg will state ’JFIF’, a rtf file will state ‘rtf’, a zip file will state >> ‘PK”, a png will state ‘PNG”, and so on. >> >> From that observation, you might try working with bin2hex or dechex and other >> such bin/hex functions PHP provides to check what the file type is in the >> header and what it reports itself to be in the extension. >> >> Additionally, you can always Google it. >> > Just to confuse the issue, both zip files and odt (Open Document) files have the > 'PK' header id. Looking around for some other formats, I found that most tgz > files (tar, gzipped) have 'vV' followed by the file name (but not all of them!). > So Jeffry will have to do some sort of a secondary test to be sure. Do a search on "magic bytes". Jonesy -- Marvin L Jones | Marvin | W3DHJ.net | linux 38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD * Killfiling google & XXXXbanter.com: jonz.net/ng.htm