dbearly@vax1.tcd.ie (10/09/90)
Recent experiments in C programming showed that it is possible to set the various attribute bits of a DOS directory. I was wondering if someone could tell me the (possible) effects and uses of setting these attributes are ? In particular I would like to know about the read-only and archive attributes. ----------------------------------------------------------------------------- dbearly@vax1.tcd.ie dbearly@unix1.tcd.ie -----------------------------------------------------------------------------
tcs@router.jhuapl.edu (10/10/90)
In article <6984.2711ef88@vax1.tcd.ie>, dbearly@vax1.tcd.ie writes: >Recent experiments in C programming showed that it is possible to set >the various attribute bits of a DOS directory. I was wondering if >someone could tell me the (possible) effects and uses of setting these >attributes are ? > > In particular I would like to know about the read-only and > archive attributes. >----------------------------------------------------------------------------- >dbearly@vax1.tcd.ie >dbearly@unix1.tcd.ie >----------------------------------------------------------------------------- Archive - On means the file has been changed since the last backup; Off means the file has not been modified. Archive is usually used with backup software. When you make a backup, the software turns the Archive bit off. Then when you wish to make an incremental backup (backing up only the files that have been changed from the last backup) it will backup only the files with the Archive bit on. Read-Only - On prevents a file from being written to or deleted. Off allows the file to be modified. Read-Only is used when you wish to protect a file from being removed. It is also used in Multi-User applications. If it isn't set On, someone else is using it and you try to execute it, you will get a "Sharing Violation Error [ARI]". Note: This doesn't prevent the file from being Renamed. Hidden - On hides this file from Command.Com commands. Hidden prevents the standard Command.Com commands from executing on it. Dir, Copy, Del, Rename etc. You can still execute the file. A Hidden data file will not be found in most cases. System - On tells DOS to consider this a file related to hardware. System is the flag used by software to indicate a file that is related to the hardware. in 99% of the cases, IBMBIOS.Sys and IBMCOM.Sys (and other related system files) are the only files that have the System flag set although I've seen my tape backup software driver with a System flag set. Directory - On indicates this is a directory and not a file. While you generally will not see Directory and Volume as a flag in a directory type of program, they are flags. If you use Norton Utilities (NU) you will see these flags on the entry. If you turn off the Directory flag, you have a (generally) 2048 byte file and all files in that directory are lost clusters. The next ChkDsk /f will return these files. A directory is just a file that contains information on the files contained in it. If you turn it off and view the file, you will see all the file names in it. Volume - On makes this file the volume label. The Volume label is a 0 byte file with the Volume flag set. If you look at the directory structure for the root, you will see a file (assuming you have a volume label on your drive). There can only be one Volume label and it has to be in the root directory (I've never tried to set two to see what happens). Disclaimer: This is the information that I have. I didn't write DOS but I have lots of experience in using it. I consider myself an expert, (IMHO) but you may not. Your milage may vary. Not valid in all states. Allow for shrinkage. Carl Schelin | "He who hesitates is not only lost, tcs@router.jhuapl.edu | but miles from the nearest exit."
mvolo@uncecs.edu (Michael R. Volow) (10/10/90)
I don't know C, but other programs such as the MSDOS version of CHMOD, and a small shareware program FILEMGR.COM or the hex editor in PCTOOLs, all can change the directory attributes. Unfortunately, you can hide a directory from DOS, but you can't make it read-only or execute only or responsive to various security levels. That is, even when one changes the attributes of a directory to read-only, DOS does not recognize it as such. DRDOS 5.0 or security programs such as PC-Vault + or HandsOff can do this. -- Michael Volow, Psychiatry, Durham VA Med Center, Durham NC 27712 919 286 0411 Ext 6933 mvolo@ecsvax.edu
browns@iccgcc.decnet.ab.com (Stan Brown, Oak Road Systems) (10/11/90)
In article <6984.2711ef88@vax1.tcd.ie>, dbearly@vax1.tcd.ie writes: > Recent experiments in C programming showed that it is possible to set > the various attribute bits of a DOS directory. I was wondering if > someone could tell me the (possible) effects and uses of setting these > attributes are ? > > In particular I would like to know about the read-only and > archive attributes. The "archive" bit means that the file was changed in some way since the last backup. One of the XCOPY options reads and sets this bit, as do FASTBACK and a number of other file backup utilities. The "read-only" bit means that the file is, er, read only. DEL/ERASE will not delete a file that is read only. The 2 paragraphs above are not 100% reliable, as some programs bypass the DOS calls that would set or interrogate these bits. The above opinions are not attributable to any other person or company. email: browns@iccgcc.decnet.ab.com Stan Brown, Oak Road Systems, Cleveland, Ohio, U.S.A. +1 216 371 0043