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Definition: Dir


(1) (DIR) (Digital Instrumentation Recorder) An earlier 19mm, helical-scan magnetic tape technology from Sony, earmarked end of life in 2004. Based on the D1 format, DIR was fast enough for sonar, radar and other high-speed data archiving. Cassettes came in 8.7GB, 43GB and 96GB capacities. Once a standard in the U.S. government, DIR was gradually replaced by LTO and SAIT technologies. See DTF, LTO, AIT and magnetic tape.




DIR Cassettes Were Huge
Next to the 4mm DAT cassette, the 96GB DIR cassette was enormous.




(2) (DIRectory) A DOS/Windows command that lists the file names in an internal or external storage drive. Originating with the CP/M operating system, Dir is widely used by Windows programmers and power users. Following are various examples:

 GENERAL DIR COMMANDS

 dir        names, date and size

 dir /w     no date and size

 dir /p     pause each screenful

 dir /ad    only folders

 dir *.     only folders or files
             without extensions

 dir *.jpg  only JPEG files
 dir *.mp3  only MP3 files
 dir *.doc  only DOC files
 dir *.exe  only executables


 BY SORT ORDER

 dir /o     folders, then files

 dir /oe    by extension a to z
 dir /o-e   by extension z to a

 dir /os    small to large
 dir /o-s   large to small

 dir /od    earliest to latest
 dir /o-d   latest to earliest


 BY FILE ATTRIBUTE

 dir /ar    read only files
 dir /ah    hidden files
 dir /aa    files to be archived
 dir /as    system files



Find Duplicate Files
The following example finds all files named X.BAT anywhere in the C: drive, because the command is initiated at the root of the drive (C:\>):

     C:\>dir x.bat /s