Home » Unix file naming convention [closed]

Unix file naming convention [closed]


. is used to separate a filetype extension, e.g. foo.txt.

- or _ is used to separate logical words, e.g. my-big-file.txt or sometimes my_big_file.txt. - is better because you don’t have to press the Shift key (at least with a standard US English PC keyboard), others prefer _ because it looks more like a space.

So if I understand your example, backup-part2-random or backup_part2_random would be closest to the normal Unix convention.

CamelCase is normally not used on Linux/Unix systems. Have a look at file names in /bin and /usr/bin. CamelCase is the exception rather than the rule on Unix and Linux systems.

(NetworkManager is the only example I can think of that uses CamelCase, and it was written by a Mac developer. Many have complained about this choice of name. On Ubuntu, they have actually renamed the script to network-manager.)

For example, on /usr/bin on my system:

$ ls -d [A-Z]* | wc -w    # files starting with a capital
$ ls -d *_* | wc -w       # files containing an underscore
$ ls -d *-* | wc -w       # files containing a minus/dash

and even then, none of the files starting with a capital uses CamelCase:

$ ls -d [A-Z]*
GET  HEAD  POST  X11  Xvnc  Xvnc4

Far more important that a particular convention is being consistent. Pick a style, and stick with it.

My take on Unix/Linux filename conventions:

  • Unix/Linux filesystems don’t inherently support the notion of an extension. The concept of a file extension completely exists as something supported by utilities such as cp, ls, or the shell you are using. I believe it is this way on NTFS as well, but I could be wrong.

  • Executables, including shell scripts, usually never have any type of extension. Scripts will have a hashbang line (i.e. #!/bin/bash) that identifies what program should interpret it.

  • Any executable that is two letters long is super important. So don’t name your executables two-letter filenames. Any file in /etc ending in tab is also super important, such as fstab, mtab, inittab.
  • Sometimes .d is appended to directory names, particularly in /etc, but this isn’t widespread (UPDATE: https://serverfault.com/questions/240181/what-does-the-suffix-d-mean-in-linux)
  • rc is widely used for configuration scripts or files, either prepending (e.g., rc.local) or suffixing (.vimrc)
  • The Unix/Linux community has never had a three-character limit on extensions and frowns upon shortening well know extensions to fit. For example, don’t use .htm at the end of HTML files on Unix/Linux, use .html.
  • In a set of files, a filename is sometimes capitalized, or in all caps, so it appears at the head of a directory listing. The classic example is Makefile in source packages. Only do this for stuff like README.
  • ~ is used to identify a backup file or a directory, as in important_stuff~, or /etc~. Many shells will expand a lone ~ to $HOME.
  • Library files almost always begin with lib. Exception is zlib and probably a few others.
  • Scripts that are called by inetd sometimes are tagged with a leading in., such as in.tftpd.
  • The ending z in vmlinuz means zipped, but I’ve never seen any other file named this way.

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