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3

The first versions of Unix happened to use 512-byte blocks in their filesystem and disk drivers. Unix started out as a pretty minimalist and low-level system, with an interface that closely followed the implementation, and leaked details that should have remained abstracted away such as the block size. This is why today, “block” still means 512 bytes in many ...


8

The terminal description is named for Linux, which provides its own console emulator (as do several other kernels). Except for FreeBSD, all of the Linux- and modern BSD-platforms get "termcap" by deriving it from the terminfo database in ncurses. Console entries are specific to the systems in which they are implemented (unlike many terminal emulators, ...


3

Blocks were more important than bytes because from the beginning, files used a given number of blocks rather than bytes on the file system. A file with one byte still took up one block on the disk. For instance the find(1) manual page from Unix 6th edition says -size n True if the file is n blocks long (512 bytes per block). ...


3

POSIX states in the Rationale for A.4.12 Pathname Resolution Paragraphs 9 and 10: In some networked systems the construction /../hostname/ is used to refer to the root directory of another host, and POSIX.1 permits this behavior. Other networked systems use the construct //hostname for the same purpose; that is, a double initial slash is used. ...


5

Another application: Blender treats a leading // as a reference to the project directory (the directory in which the .blend file is saved). Here's the relevant manual page. This is true for non-Unix-like operating systems (i.e., Windows) as well.


4

In the 1980s, SEL/Gould had a Unix operating system called UTX-32 in which //host/path was equivalent to /net/host/path in Solaris; i.e., remotely access path path on host host.  I can't find any documentation on it, so I don't know whether this was RFS or parallel evolution (or whether AT&T stole acquired it from Gould).


53

This is a compilation and index of the answers given so far. This post is community wiki, it can be edited by anybody with 100+ reputation and nobody gets reputation from it. Feel free to post your own answer and add a link to it in here (or wait for me to do it). Ideally, this answer should just be a summary (with short entries while individual other ...


6

Following the lead from this answer. And reading page 2-15 from the manual from Bitsavers (thanks @grawity). Shared Data The second design principle of the Domain/OS distributed file system, sharing by default, implies a global uniform name space. The name space of the distributed file system appears to users like that of a giant timesharing file ...


4

I have a vague memory that the //host/path notation was used on AT&T SysV.3 as part of its RFS Remote File Sharing implementation. This was eventually abandoned around the time SysV.4 was released in favour of the simpler but more popular NFS from Sun Microsystems. However, I cannot find any concrete references to the syntax, and the documentation I ...


12

Several decades ago, Tektronix Utek (BSD 4.2 based Unix, first on National Semiconductors 32016 CPUs then Motorola 68020s) was providing something called DFS (distributed file system) under which //foo/bar was referring to the /bar file on the foo dfs server. It was later obsoleted by Sun's NFS. Unfortunately, I haven't reference yet to back that but I ...


13

Do some applications running on Unix-likes —if not the system's API— treat //foo/bar Paths specially? I am aware of Perforce which uses //depot/A/B/C/D Paths to refer to the Depot. Perforce also supports //Client/C/D Paths, when the Client is pointing to //depot/A/B/. Here, local FileSystem may not have these Paths. p4 filelog //depot/A/B/C/D will show ...


5

It will be no easy task to find "historic documents" about this decision, but quoting another answer from the StackExchange umbrella, you will find what I also think is the most appropriate answer to your question: to avoid "sh## happens" scenario: bash: Why is . not in the path by default? You answered correctly your own question, that's exactly why ...



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