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LC_TIME portability (and other locale settings)

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 ...
Juan's user avatar
  • 884
0 votes
1 answer
68 views

Why did Red Hat relocate Apache to /usr/sbin

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 ...
JakeS's user avatar
  • 11
-1 votes
1 answer
58 views

Are any modifications to the FHS being worked on (by the Linux Foundation)?

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 ...
RokeJulianLockhart's user avatar
0 votes
1 answer
56 views

What does "site-wide" mean?

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-...
robertspierre's user avatar
7 votes
1 answer
2k views

How should I interpret the fact that a Unicode code point is shown in two completely different ways in two different terminal emulators?

This is kind of a spin off from an older question I asked. Here's the screenshot from that question: In the bottom left is URxvt, and you can see a lighting bolt-like icon at the beginning of the ...
Enlico's user avatar
  • 1,677
0 votes
1 answer
64 views

What is the standard for "traditional Unix file system permissions"?

I am writing about Unix file permissions - i.e. user/group/world, read(4)/write(2)/execute(1), chmod(), etc. I would like to point the reader to a standard (e.g. Markdown have the CommonMark standard, ...
d4nyll's user avatar
  • 185
8 votes
2 answers
265 views

Is /root a hard requirement for a modern Linux system? What about POSIX? UNIX?

I moved /root to /home/root and changed the appropriate entry in /etc/passwd in my Linux system quite some time ago and everything's worked until recently when I discovered that at least the firejail ...
Artem S. Tashkinov's user avatar
0 votes
1 answer
66 views

How to interpret "functions ... may also be defined as macros"?

For the sake of public record, I'm asking here at SE rather than on the standardization mailing list, so that it'd be more accessible to people. With practically every headers that specify functions (...
DannyNiu's user avatar
  • 620
0 votes
1 answer
92 views

How to use one table (ods) file as a base for another table file?

I have an accounting ledger table (.ods) file which should be the base for other table files. This table file should be the base for other table files such as: 2023.ods 2024.ods 2025.ods These are ...
searcher's user avatar
3 votes
0 answers
5k views

When to clean up /var/tmp?

/var/tmp is not defined in POSIX, but is defined in FHS: 5.15. /var/tmp : Temporary files preserved between system reboots 5.15.1. Purpose The /var/tmp directory is made available for programs that ...
Jonas Stein's user avatar
  • 4,138
6 votes
0 answers
2k views

Why is unistd.h named the way it is?

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 ...
Lukas Velikov's user avatar
0 votes
1 answer
66 views

Single Unix Specification version 4 (Issue 7) moved bunch of Real-Time APIs to Base, What Next?

While reading the standard, I noticed that bunch of APIs were, Introduced in Issue 5 for alignment with POSIX realtime APIs, Marked for option group membership in Issue 6, and Moved to Base in ...
DannyNiu's user avatar
  • 620
2 votes
3 answers
2k views

Cat alternatives for writing terminal input to file?

When I want to quickly write something to a file that either get's pasted or manually input from the terminal, a quick cat > something.txt and Ctrl+D to close, is a nice shortcut. However of course ...
UserZer0's user avatar
  • 135
2 votes
2 answers
613 views

Are there "non-standard" streams in Linux/Unix?

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 ...
user56834's user avatar
  • 135
0 votes
1 answer
344 views

How to understand the naming convention of IEEE standards?

I see some IEEE standards from https://pubs.opengroup.org/onlinepubs/9699919799/: POSIX.1-2017 is simultaneously IEEE Std 1003.1™-2017 and The Open Group Technical Standard Base Specifications, Issue ...
smwikipedia's user avatar
  • 1,203
2 votes
0 answers
49 views

Does POSIX specify sed -E? [duplicate]

sed uses basic regular expressions (BRE) by default. Some implementations offer an option to switch to extended regular expressions instead. GNU sed introduced the -r option to do so in version 3.01 ...
Socowi's user avatar
  • 635
2 votes
0 answers
144 views

Netflix and Linux and VM

I heard that Netflix needs PlayReady 3.0, Widevine, HEVC 10 bits de/encoder, HDCP 2.2... to play 4K/UHD contents So I want to know if Linux support these technologies, and if Netflix support those ...
aaa's user avatar
  • 167
2 votes
1 answer
156 views

Why does ISO C / POSIX time() have an optional pointer argument

ISO C / POSIX declare the time() function like this: time_t time(time_t *tloc); The documentation says: The time() function shall return the value of time in seconds since the Epoch. The tloc ...
Thomas Perl's user avatar
-1 votes
1 answer
70 views

Is Perl a standard for *nix hosting companies? [closed]

I never worked with Perl but in this community I bump time and again on recommendations to work with it, often as a "completion" for shell scripts. Is Perl a standard for *nix hosting ...
variableexpander's user avatar
0 votes
1 answer
184 views

Get the output of a remote ssh to local

I'm able to get the output of a failing lp command from a remotehost to my local script like below: until ssh -q root@remotehost 'lp -d Brother_HL_L2350DW_series /root/moht/Printed/`basename "$...
Ashar's user avatar
  • 511
17 votes
2 answers
2k views

View POSIX draft standards

The GNU sed manpage says: The -E option switches to using extended regular expressions instead; it has been supported for years by GNU sed, and is now included in POSIX. However, POSIX Issue ...
Tom Hale's user avatar
  • 31.2k
2 votes
2 answers
359 views

Is a NEWLINE character at line end required by LSB (Linux Standard Base)?

Both POSIX and SUS (Single UNIX Specification) define a line as A sequence of zero or more non-<newline> characters plus a terminating <newline> character. Many distributions are more ...
Mario Nette's user avatar
13 votes
2 answers
1k views

What is POSIX awk's stance on null byte in variables/printf?

Is it legal to print null bytes using awk's printf function according to POSIX? The POSIX standard of awk does not seem to explicitly mention it either way. Real world implementations differ in how ...
graywolf's user avatar
  • 941
1 vote
1 answer
117 views

Why is it legal to have white space before builtin function in awk?

I am trying to understand how busybox's awk works so I'm looking into the standard and hit weird thing which I do not fully understand why is legal. Standard ( https://pubs.opengroup.org/onlinepubs/...
graywolf's user avatar
  • 941
2 votes
0 answers
41 views

RHEL based distros and FHS (and postgres)

Under CentOS, i see postgres config files are located in '/var/lib/...' (instead of '/etc'). In FHS specifications, under '/var/lib' (chapter 5, section 8.1) it is specified: This hierarchy holds ...
user374819's user avatar
2 votes
2 answers
135 views

Why does lvm2 use mixed case UUIDs?

I noticed that lvm2 objects use mixed case UUIDs: ~ # lvdisplay ...
WoJ's user avatar
  • 1,575
-4 votes
2 answers
112 views

Utility dependence in shell

I know that the "layer" architecture of any *nix OS is kernel-shell-utility ("inner to outer"). if we installed say Debian-Server and got some CLI utilities with it, Should all these utilities work ...
user avatar
0 votes
0 answers
58 views

Why does mtab live in etc? [duplicate]

Something I've never understood with linux is why a status file is stored under /etc. As far as I know /etc/ is for configuration (relatively static) configuration files. But /etc/mtab shows the ...
ARF's user avatar
  • 165
0 votes
2 answers
327 views

How to advocate for GNU to add a "--json" parameter for all CLI commands to be compliant? [closed]

Call me a dreamer, but imagine a world where "every" CLI tool we use had an option to produce a stable output, say in JSON.  Programmatic use of CLI tools like ls, free, df, fdisk would be a ...
Slawomir's user avatar
  • 165
3 votes
2 answers
897 views

Why does Apple care if macOS is officially called UNIX? [closed]

Based on my understanding, if the owners of an OS want their OS to be officially called UNIX, they must get a certification from The Open Group. macOS version 10.14 Mojave, as well as some (or maybe ...
user339981's user avatar
8 votes
1 answer
6k views

WM_CLASS vs WM_INSTANCE?

When I run xprop I get a class string that has two values, one of them i3 calls an instance, the other a class, for example on chromium-browser the xprop utility will return something like this, ...
Evan Carroll's user avatar
  • 31.7k
3 votes
2 answers
2k views

Different standards of ELF (SysV vs TIS) and Linux?

There are at least two standards of Executable and Linkable Format (ELF), one of them System V Application Binary Interface AMD64 Architecture Processor Supplement (With LP64 and ILP32 Programming ...
Evan Carroll's user avatar
  • 31.7k
8 votes
2 answers
2k views

Is Linux considered XSI compliant or largely so?

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 ...
Tim's user avatar
  • 103k
2 votes
0 answers
289 views

Move from single configuration files to .d directories in Linux

Note: I am not asking specifically about rc as in The rc0.d,rc1.d,... directories in /etc Many guides on the internet and this website remember the days when Linux distributions by default used files ...
cat's user avatar
  • 3,478
0 votes
1 answer
209 views

linux + write both standard output and stand error to log and to console

log=/tmp/log.txt the follwing syntax write all standard output and stand art error to log.txt file exec > $log 2>&1 what we want is to write both standard output and stand art error to log.txt ...
jango's user avatar
  • 423
10 votes
2 answers
3k views

Does POSIX standardize the file descriptor numbers?

Does POSIX mandate that stdin is 0, stdout is 1 and stderr is 2 or is this only a convention? Do other systems diverge from that convention or is it a safe assumption?
Evan Carroll's user avatar
  • 31.7k
1 vote
3 answers
2k views

Do variables and aliases fall under the same category?

This is a terminology/architecture question. Some of the most basic implementations for easier control of a system are variables and aliases (and some might add symlinks). Both variables and ...
Arcticooling's user avatar
1 vote
3 answers
2k views

how to send standard output and standard error to two files

I use the following syntax in order to send standard output and standard error to $log file log=/var/tmp/install.log info=/tmp/info.log exec > $log 2>&1 how to redirect both standard ...
yael's user avatar
  • 13.4k
1 vote
1 answer
3k views

How to make sed regex syntax work as python or javascript? [duplicate]

I have asked a question insert a string to a list variables in text file [use sed] In which @RomanPerekhrest showed me a different regex syntax. \(=([^)]*\)) can capture [^)]* as group 1 . This is ...
Mithril's user avatar
  • 525
3 votes
1 answer
305 views

Can $PAGER contain spaces?

I'm writing an application from which I want to run a user-specified pager. The standard way to do this seems to be to look at the PAGER environment variable. I'm unclear as to whether this is a ...
Att Righ's user avatar
  • 1,226
1 vote
2 answers
464 views

Sendmail compatibility interface

Postfix (and lots of other stuff) claim they offer sendmail compatible interface. Since I want to write my own sendmail implementation, I was wondering what that actually means. Is there anything RFC-...
graywolf's user avatar
  • 941
4 votes
3 answers
13k views

Unprintable characters as input in command line

I've got a program that requires some unprintable characters like 0x0F (ctrl+o) as input to execute the intended part of the program. 0 000 00 NUL &#000; Null ...
FargolK's user avatar
  • 1,657
11 votes
1 answer
817 views

Confusion about changing meaning of arguments and options, is there an official standard definition?

I came across a confusing variation in the understanding what options and arguments are with regard to the syntax of commands. For instance, I encountered definitions like: command -a -b -c d e f ...
sharkant's user avatar
  • 3,740
8 votes
1 answer
3k views

Does the UNIX standard require case-sensitive filesystems?

One answer to this question mentions the UNIX 03 certification of OSX. Now AFAIK the standard file system of OSX is/was HFS, which "saves the case of a file that is created or renamed but is case-...
Martin Schröder's user avatar
2 votes
1 answer
119 views

Any reason why find does not merge multiple slashes into one?

Is it true that find is not supposed to be doing even the most simple path unification/simplifications operations, such as coalescing multiple successive slashes together (which would be equivalent to ...
phk's user avatar
  • 5,983
111 votes
5 answers
13k views

Do progress reports/logging information belong on stderr or stdout?

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 ...
terdon's user avatar
  • 244k
7 votes
1 answer
25k views

Recommended GID for users group in Linux (100 or 1000)?

I have several GNU/Linux installations that share home and data directories. Over time some user files in these directories have received the group ID 100 (users group under some variants of Linux), ...
Ned64's user avatar
  • 8,924
0 votes
2 answers
61 views

Heuristics for making use of or dismissing old documentation [closed]

Getting them as search results or following reference links, I often come across documentation produced some time ago. A few months, a few years. Sometimes the documents are marked as deprecated or ...
user avatar
21 votes
2 answers
5k views

An official standard / convention for a file extension for shell scripts to source

I was wondering if there is a convention for file type extensions for shell scripts you want to source instead of run. For example: If I want to run this script in a subshell. ./script.sh If I ...
Mateusz Piotrowski's user avatar
1 vote
1 answer
96 views

Where can I find the most recent dictionary of standard Linux Audit event fields?

I am writing a converter which takes Linux Audit logs as input. I tried to find the most recent dictionary file where all the valid names of the fields are defined. I've found such a file[1] but the ...
Mateusz Piotrowski's user avatar