Questions tagged [standard]
The standard tag has no usage guidance.
100
questions
0
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1
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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-...
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votes
1
answer
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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 ...
- 1,471
0
votes
1
answer
56
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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, ...
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2
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251
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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 ...
- 26.6k
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1
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52
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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 (...
- 622
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1
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85
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 ...
- 11
2
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0
answers
4k
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
...
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4
votes
0
answers
1k
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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 ...
- 149
0
votes
1
answer
61
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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 ...
- 622
2
votes
3
answers
1k
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 ...
- 137
1
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2
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446
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Are there "non-standard" streams in Linux/Unix?
The so-called "standard streams" in Linux are stdin,stdout,stderr. But they must be called "standard" for a reason. Are there non-standard streams? And are these non-standard ...
- 125
0
votes
1
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268
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 ...
- 1,173
2
votes
0
answers
47
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 ...
- 601
2
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0
answers
124
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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 ...
- 157
2
votes
1
answer
128
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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 ...
- 213
-1
votes
1
answer
63
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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 ...
0
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1
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149
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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 "$...
- 459
16
votes
2
answers
2k
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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 ...
- 28.9k
2
votes
2
answers
286
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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 ...
- 61
13
votes
2
answers
1k
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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 ...
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1
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1
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95
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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/...
- 901
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0
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35
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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 ...
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2
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124
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Why does lvm2 use mixed case UUIDs?
I noticed that lvm2 objects use mixed case UUIDs:
~ # lvdisplay
...
- 1,455
-4
votes
2
answers
102
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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 ...
user149572
0
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0
answers
56
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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 ...
- 165
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2
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269
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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 ...
- 155
2
votes
2
answers
806
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 ...
- 39
8
votes
1
answer
5k
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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,
...
- 29k
2
votes
2
answers
2k
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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 ...
- 29k
7
votes
2
answers
2k
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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 ...
- 99.1k
2
votes
0
answers
260
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 ...
- 3,438
0
votes
1
answer
195
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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 ...
- 413
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?
- 29k
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3
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1k
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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 ...
1
vote
3
answers
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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 ...
- 12.7k
1
vote
1
answer
2k
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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 ...
- 535
3
votes
1
answer
284
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 ...
- 1,176
1
vote
2
answers
413
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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-...
- 901
4
votes
3
answers
11k
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 � Null ...
- 1,629
11
votes
1
answer
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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
...
- 3,570
8
votes
1
answer
2k
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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-...
- 939
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1
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115
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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 ...
- 5,893
108
votes
5
answers
12k
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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 ...
- 235k
6
votes
1
answer
23k
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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), ...
- 8,546
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votes
2
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55
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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 ...
user147505
21
votes
2
answers
5k
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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 ...
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1
vote
1
answer
86
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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 ...
- 4,623
16
votes
2
answers
8k
views
Is there a Linux distro that's UNIX certified?
Is there a Linux distribution certified with the Single UNIX Specification? What are the primary reasons that most distributions don't get certified?
- 269
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2
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bash: --argument vs -arg [duplicate]
In most scripts (but mainly bash) it's commonplace to see some arguments that are configured like so:
bash-4.3:$ command --longer-argument -la
Where did this originate from? I'm mainly just curious ...
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3
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4k
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What is the unix mailbox format?
man git-format-patch makes reference of the UNIX mailbox format which is a term I am unfamiliar with.
A google search for "UNIX mailbox format" and similar expressions lists many hits with the term ...
- 2,201