Suppose I have downloaded the source of some software I want to install *just for myself*, not system-wide; say Emacs or whatever. Typically the source is downloaded zipped, then it's unzipped in some directory. This directory contains files like "Makefile", "LICENSE", "configure", and so on. **Question: where should such a source directory be stored (for future check or use) within one's $HOME directory?** I checked the [XDG Base Directory Specification](https://specifications.freedesktop.org/basedir-spec/latest/) , but I don't manage to recognize any guidelines there – also because I'm a noob and I don't know if such files are considered "data files" or "state files" or other technical denomiations. A lot of (old) questions ask about where to install the local *executables*, for instance [this question](https://askubuntu.com/q/1148/1519798) or [this question](https://unix.stackexchange.com/q/127076/515980) or [this question](https://unix.stackexchange.com/q/316765/515980) (my system Kubuntu 24.04 confirms that ~/.local/bin is a good place, it's added to $PATH by default). Only [this question](https://unix.stackexchange.com/q/362642/515980) asks about the source files, but it seems to refer to system-wide ones, not local-user ones. It seems strange to me to have to save the source in system-wide /usr/src or the like.

For example, Ubuntu 25.10 plan to raise the required RISC-V ISA profile family to RVA23. How can I verify if this release is RVA23 compatible? Is there any efficient test tools I can use? I know that RVA20/23 profile includes a lot of system components like compiler, kernel etc. If no tool is available for test its compatible for RVA20/23, should I just check each of the necessary components like gcc, kernel, llvm? Is there a list for checking?

Java community use 4 spaces as the unit of indentation. [1] Ruby community use 2 spaces that is generally agreed-upon. [2] What's the standard for indentation in shell scripts? 2 or 4 spaces or 1 tab?

From APUE > The Single UNIX Specification, a superset of the POSIX.1 standard, > specifies additional interfaces that extend the functionality provided > by the POSIX.1 specification. POSIX.1 is equivalent to the Base > Specifications portion of the Single UNIX Specification. > > The X/Open System Interfaces (XSI) option in POSIX.1 describes > optional interfaces and defines which optional portions of > POSIX.1 must be supported for an implementation to be deemed > XSI conforming. These include file synchronization, thread stack > address and size attributes, thread process-shared synchronization, > and the > _XOPEN_UNIX symbolic constant (marked ‘‘SUS mandatory’’ in Figure 2.5). Only XSI-conforming implementations can be called UNIX systems. Is it correct that SUS consists exactly of POSIX and XSI? Is it correct that Linux (or Ubuntu, Debian in particular) is POSIX compliant? Is Linux (or Ubuntu, Debian in particular) considered XSI compliant or largely so? I ask this because then I will know whether the parts in APUE labelled for XSI apply to Linux (or Ubuntu, Debian in particular). I am mainly interested in API, so does that mean Linux kernel suffices?

##### Context 1. Through a bug report and discussion about KDE Plasma's user management KConfig Module silently failing to support commas inside the full name field, I recently came to realise that parsing the GECOS field in /etc/passwd is a rather unstandardised endeavour, [\[2\]] for some applications support the comma-delimited values, [\[5\]] whereas others consider the entire content to be the user's full name. [\[3\]] 1. When I discussed this with the chfn developers at [github.com/util-linux/util-linux/discussions/3589#discussioncomment-13270218](https://github.com/util-linux/util-linux/discussions/3589#discussioncomment-13270218:~:text=Maintainer-,POSIX%20defines%20the%20/etc/passwd%20format%2C%20but%20not%20the%20GECOS%20subfields%20and%20separators.,-The%20use%20of) , I was advised that this was the purview of POSIX: > POSIX defines the /etc/passwd format, but not the GECOS subfields and separators. 1. Consequently, I intended to file an ommission bug at The Austin Group MantisBT instance: [\[4\]] However, upon further research, POSIX.1 (The Open Group Base Specifications Issue 8) is too narrow, so I tried The Single UNIX Specification Version 4. Unfortunately, this explicitly states: [\[1\]] > One thing that becomes apparent working with the Single UNIX Specification is its focus on application development. The Single UNIX Specification is similar to the User's and Programmer's Reference Manuals on Berkeley or System V systems. > > Matters of system management are not part of this specification. Directory organization is not discussed beyond the simple few directories and devices that applications generally use. User management discussions do not appear. There is no discussion of such files as /etc/passwd or /etc/groups, since an application's access to the information traditionally kept in these files is through programmatic interfaces such as getpwnam() and getgrnam(). ##### Question Consequently, does *any* organisation exist, that I can petition to, to standardise the escape sequences of /etc/passwd's GECOS field, so that [those who use commas in their names](https://english.stackexchange.com/revisions/324077/2#content:~:text=Organization%20is%20better%20than%20randomness,ordered%20lists%20by%20last%20name.) can? [\[1\]]: https://unix.org/version4/overview.html#:~:text=One%20thing%20that%20becomes%20apparent,such%20as%20getpwnam()%20and%20getgrnam() . [\[2\]]: https://discuss.kde.org/t/why-does-the-users-kcm-prevent-adding-certain-characters-to-names/34772/3?u=rokejulianlockhart#post_3:~:text=If%20I%20understand%20correctly%2C%20the,defined%20in%20the%20first%20place . [\[3\]]: https://discuss.kde.org/t/why-does-the-users-kcm-prevent-adding-certain-characters-to-names/34772/3?u=rokejulianlockhart#post_3:~:text=the%20first%20place.-,There%E2%80%99s%20still%20some%20software%20out%20there%20that%20doesn%E2%80%99t%20recognize%20the%20GECOS%20subfields%20in%20the%20first%20place.%20That%20software%20treats%20commas%20as%20normal%20characters%2C%20confusing%20software%20that%20does%20recognize%20the%20subfields.,-1 [\[4\]]: https://www.reddit.com/r/unix/comments/cf21sh/comment/muj126e/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button#:~:text=The%20SUS%20V4%20corresponds%20to,selext%20Issue%207%20+%20TC2 [\[5\]]: https://unix.stackexchange.com/revisions/541197/1#content:~:text=The%20de%20facto%20authoritative%20sources%20for%20this%20information%20are%20sendmail%20server%20and%20finger%20client%20implementations.%20Implementations%20for%20BSDs%20and%20Solaris%20are%20open%20source%2C%20and%20all%20of%20them%20would%20seem%20to%20agree%20on%20the%20above%20rules .

While [pondering whether IEEE 1003.1-2017 forbids race-condition safe ln -f](https://unix.stackexchange.com/questions/794236/idiomatic-way-of-generating-a-unique-filename/794239#comment1526091_794239) , it occurred to me: Even if this is really an unfortunate definition (which GNU coreutils' ln thankfully ignores), I would have no way to say "hey, dear standardizers, next iteration, maybe don't specify this broken thing, and instead demand this safe thing, or at least don't prohibit safe implementation". How does the evolution of the POSIX / IEEE 1003.1 standard actually happen? How can the interested public participate, if at all?

Is there an official POSIX, GNU, or other guideline on where progress reports and logging information (things like "Doing foo; foo done") should be printed? Personally, I tend to write them to stderr so I can redirect stdout and get only the program's actual output. I was recently told that this is not good practice since progress reports aren't actually errors and only error messages should be printed to stderr. Both positions make sense, and of course you can choose one or the other depending on the details of what you are doing, but I would like to know if there's a commonly accepted standard for this. I haven't been able to find any specific rules in POSIX, the GNU coding standards, or any other such widely accepted lists of best practices. We have a few similar questions, but they don't address this exact issue: * https://unix.stackexchange.com/q/79315/22222 : The accepted answer suggests what I tend to do, keep the program's final output on stdout and anything else to stderr. However, this is just presented as a user's opinion, albeit supported by arguments. * https://unix.stackexchange.com/q/8813/22222 : This is specific to help messages but cites the GNU coding standard. This is the sort of thing I'm looking for, just not restricted to help messages only. So, are there any official rules on where progress reports and other informative messages (which aren't part of the program's actual output) should be printed?

Are basic system administrator utilities such as useradd or adduser standardized? If so, where can I find the specs? (POSIX doesn't seem to encompass those, but I might need to take a better look).

This page describing the Shell grammar has the following paragraph in the "Shell Grammar Rules" section: > 1. [Command Name] > >When the TOKEN is exactly a reserved word, the token identifier for that reserved word will result. Otherwise, the token WORD will be returned. Also, if the parser is in any state where only a reserved word could be the next correct token, proceed as above. This rule applies rather narrowly: when a compound list is terminated by some clear delimiter (such as the closing fi of an inner if_clause) then it would apply; where the compound list might continue (as in after a ;), rule 7a (and consequently the first sentence of this rule) would apply. **In many instances the two conditions are identical**, but this part of this rule does not give licence to treating a WORD as a reserved word unless it is in a place where a reserved word must appear. In the highlighted part (i.e. "In many instances the two conditions are identical"), what are the "two conditions"? What are the instances where they are "identical", and what are some instances where they are not "identical"? I think I understand the meaning behind this paragraph (combined with **rule 7a** from below): the parser will only "generate" a RESERVED WORD token if either: - the parser is in a state where it expects a new command and the next TOKEN is "exactly a RESERVED WORD", or - the parser is in a state where only a RESERVED WORD token should be appear (if the parser did not allow for this, a parser error would be generated) What I am failing to understand is the exact wording of the author. If I am not mistaken, the first two sentences of the quoted paragraph apply when the parser is in a state where it expects a new command. The third sentence applies when the parser is in a state that requires a RESERVED WORD token to appear. Is the "first condition": the parser is in a state where it expects a new command + the TOKEN is exactly a RESERVED WORD? And the second condition: "the parser is in a state that requires a RESERVED WORD token to appear? If so, I do not see any instance where the "two conditions are identical". I would greatly appreciate it if someone could explain what the author meant by using the quoted wording. Thank you!

I see POSIX mentioned often and everywhere, and I had assumed it to be the baseline UNIX standard.. until I noticed the following excerpt on a Wikipedia page: [*The Open Group*](http://en.wikipedia.org/wiki/The_Open_Group) > The Open Group is most famous as the > certifying body for the UNIX > trademark, and its publication of > the *Single UNIX Specification > technical standard*, ***which extends > the POSIX standards and is the > official definition of a UNIX system***. If the official definition of a UNIX system is an extension of POSIX, then what exactly is POSIX? ,,, It surely seems to be a touchstone of the UNIX world, but I don't know how it fits into the overall picture.

I was wondering how the "GUI" of a command line application is communicated over a network. Most of the time, it's quite simple (plain text / input) but sometimes it's more complex (aptitude). Is it defined by some sort of standard so that anyone can write their own terminal and that all terminal implementations behave in the same way (colors, positioning, etc.)?

I am having some issues in using an answer provided on this site for [this question about a sed command to replace a blank line with two other lines of content](https://unix.stackexchange.com/questions/13688/sed-command-to-replace-a-blank-line-with-two-lines-of-content) , and it was brought up if the sed command on Mac OS (10.6.7 for me) is different. I don't think that it is, but was wondering if others on this site thought differently.

It seems that Linux and FreeBSD (at least) have different notions of how presentation of time is implemented in different locales (LC_TIME), notably but not entirely in how the hour of day is presented (12 hr am/pm style or 24 hour). Linux (as seen on recent Fedora & Ubuntu): env LC_TIME=C.UTF-8 TZ=UTC date --date 22:22:22 '+%H %T %p, %r, %+, %Ec' ; env LC_TIME=en_US.UTF-8 TZ=UTC date --date 22:22:22 '+%H %T %p, %r, %+, %Ec' 22 22:22:22 PM, 10:22:22 PM, %+, Fri May 17 22:22:22 2024 22 22:22:22 PM, 10:22:22 PM, %+, Fri 17 May 2024 10:22:22 PM UTC FreeBSD: env LC_TIME=C.UTF-8 TZ=UTC date -v 22H -v 22M -v 22S '+%H %T %p, %r, %+, %Ec' ; env LC_TIME=en_US.UTF-8 TZ=UTC date -v 22H -v 22M -v 22S '+%H %T %p, %r, %+, %Ec' 22 22:22:22 PM, 10:22:22 PM, Fri May 17 22:22:22 UTC 2024, Fri May 17 22:22:22 2024 22 22:22:22 PM, 10:22:22 PM, Fri May 17 22:22:22 UTC 2024, Fri May 17 22:22:22 2024 My questions are: Is there a standard that defines presentation for various locale specific settings (like LC_TIME)? If so, where is the standard documented?

I run Apache http servers on Red Hat and Oracle Linux machines. The account requires that only packages from the Red Hat or Oracle repositories be used. That’s fine , they work and are reasonably current. So a new SA joined and was shocked and amazed that the apachectl script and httpd image are being put into /usr/sbin, stating that in all the years they’ve been running Unix systems none ever were done like that and it’s a contravention of the Unix way. Well I don’t really care one way or the other but maybe he has a point. Does anyone know why Red Hat chose this arrangement?

https://unix.stackexchange.com/a/227625/386242 explains the myriad benefits of a simpler and more consistent filesystem hierarchy, but also that without any cross-OS standardization, such efforts are as much of a disadvantage as they are an advantage. Consequently, is the Linux Foundation drafting a Filesystem Hierarchy Standard 3.1 or 4.0?

The so-called "standard streams" in Linux are stdin, stdout, and stderr. They must be called "standard" for a reason. Are there non-standard streams? Are those non-standard streams fundamentally treated differently by the kernel?

There are at least two standards of [Executable and Linkable Format (ELF)](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) , one of them * [System V Application Binary Interface AMD64 Architecture Processor Supplement (With LP64 and ILP32 Programming Models) Version 1.0](https://raw.githubusercontent.com/wiki/hjl-tools/x86-psABI/x86-64-psABI-1.0.pdf) * [Tool Interface Standard (TIS) Executable and Linking Format (ELF) Specification Version 1.2](http://refspecs.linuxbase.org/elf/elf.pdf) The older one, the TIS ELF Standard 1.2 is 106 pages while the SysV ABI is 157 pages but covers ELF only on pages 63-86 (23 pages). How do these two standards relate to each other? And which one does Linux and GNU Linker use? What is the Tool Interface Standard?

I'm reading man hier, which says: > /etc > > Contains configuration files which are local to the machine. Some larger software packages, like X11, can have their own subdirectories below /etc. **Site-wide** configuration files may be placed here or in /usr/etc. Nevertheless, programs should always look for these files in /etc and you may have links for these files to /usr/etc. What does "site-wide" mean? Is it synonymous with "system-wide", that is, for all users on the system?

Similar in spirit to this question about the etymology of linux commands , I'm curious about the origin of the name of unistd.h. **Does anyone know *for certain* what unistd.h stands for? If unistd.h was meant to be read as "Unix standard header", why wasn't it named unixstd.h?** From the Open Group's description of unistd.h (emphasis mine): > unistd.h - **standard** symbolic constants and types From Wikipedia (emphasis mine): > In the C and C++ programming languages, unistd.h is the name of the > header file that provides access to the POSIX operating system API. It > is defined by the POSIX.1 standard, the base of the Single **Unix** > Specification, and should therefore be available in any > POSIX-compliant operating system and compiler. Putting two and two together, it looks like unistd.h is likely a combination of *Unix* (uni) and *standard* (std), resulting in a "Unix standard header". Barath Ravikumar and Vicky Chijwani posit this in an answer to another, unrelated Stack Overflow question: > `` , stands for unix standard header ,the name says it all. > unistd **could just as well stand for "universal standard header"** (I realize that sounds a bit ridiculous). The point is, they should've named it unixstd.h -- instant clarity by adding just one character. If this is true, then it's possible that the omission of a single x character has helped spawn more than a few questions about the C standard library and why unistd.h isn't part of it (example 1 , example 2 , example 3 ).

This is kind of a spin off from [an older question I asked](https://unix.stackexchange.com/questions/715076/how-can-i-have-colored-emoji-in-urxvt) . Here's the screenshot from that question: - In the bottom left is [URxvt](https://wiki.archlinux.org/title/Rxvt-unicode) , and you can see a lighting bolt-like icon at the beginning of the prompt, that's "\ue00a"; - in the bottom right is xfce-terminal from [Xfce](https://wiki.archlinux.org/title/Xfce) , and you can see that it renders the very same "\ue00a" Unicode point in a very different way! I was under the impression that when I read something like "\ue00a", "\u263b", "\u1d43d" and so on, I'm most likely looking at the identity of a symbol, as defined by Unicode. However, how strange would the definition need to for it to allow 2 terminal emulators to show it so differently? Incidentally, I don't know how much of this is due to the terminals and how much to the fonts. I am asking this question (like the other I linked) in order to get a better understanding of the whole matter.