Filesystems and case-insensitivity [LWN.net]

Filesystems and case-insensitivity

Posted Dec 7, 2018 11:09 UTC (Fri) by Wol (subscriber, #4433)
In reply to: Filesystems and case-insensitivity by ScottMinster
Parent article: Filesystems and case-insensitivity

> But leaving that aside for the moment, what is the gain? I've been working on case sensitive Linux file systems for many years, and never felt the need to have "level1.MAP" really load "level1.map".

Because you're a programmer used to thinking in byte strings.

I *still* have problems because users insist on knowing whether email addresses have capital letters or not (they are case-insensitive, for historical reasons, because a lot of the early systems mangled case).

So the short answer is, YOU may not feel the gain, but a lot of other people WILL.

(Along the same lines, I remember being sent a second copy of some newsletter because "some people said they couldn't read the attachment". Ie pretty much all Windows systems, because the sender had somehow lost the extension and those systems didn't recognise the file "newsletter" as a pdf. Of course, my gentoo system didn't give a monkeys :-)

Cheers,
Wol

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Filesystems and case-insensitivity

Posted Dec 7, 2018 11:45 UTC (Fri) by gioele (subscriber, #61675) [Link] (2 responses)

> I *still* have problems because users insist on knowing whether email addresses have capital letters or not (they are case-insensitive, for historical reasons, because a lot of the early systems mangled case).

These users are right: the local-part of an email address _is_ case sensitive. Only the domain is case insensitive.

RFC 5321, section 2.4 [1]:

> The local-part of a mailbox MUST BE treated as case sensitive. Therefore, SMTP implementations MUST take care to preserve the case of mailbox local-parts. In particular, for some hosts, the user "smith" is different from the user "Smith". However, exploiting the case sensitivity of mailbox local-parts impedes interoperability and is discouraged. Mailbox domains follow normal DNS rules and are hence not case sensitive.

[1] https://tools.ietf.org/html/rfc5321#section-2.4

Filesystems and case-insensitivity

Posted Dec 7, 2018 16:31 UTC (Fri) by smurf (subscriber, #17840) [Link] (1 responses)

Its cast must be preserved in transit but terminal MTAs are free to treat them as case insensitive. Most do, these days.

Filesystems and case-insensitivity

Posted Dec 8, 2018 23:37 UTC (Sat) by zlynx (guest, #2285) [Link]

Fedora's default Exim configuration did not make it insensitive. I had to add that myself because my server was rejecting a lot of mail, mostly from Gmail users randomly capitalizing things.

> lowercase_local:
> driver = redirect
> data = ${lc:${local_part}}