What is POSIX?
UNIX has spread and a lot of derivatives have emerged, but it's becoming less cohesive, so it's stipulated to maintain compatibility.
There is an explanation like this.
What was the situation like?
(Sorry if the sentence below is incorrect.)
For example,
#include<stdio.h>
void main(void) {printf("lol");}
To run this program on the compiled link operating system, click
This program is within the scope of standard C, so it would be good if there was a library for that OS that complies with standard C, right?
Conversely, if you want to port this program to another operating system
You need a library specified in standard C for the OS to be ported to, right?
even if it's the same UNIX derivative
The libraries used to create programs that run on that OS were unique to each OS, so
For example
a program with a library dedicated to unix derivatives
If you try to take it to another unix derivative os and compile it, you can't use the library dedicated to the port source unix (it's not available at the port), so
Incompatible source code level
...so
Did you try to rule out APIs in POSIX to improve portability?
One more
Is the API defined in posix not available in standard C?
unix posix
Perhaps the technical reasons in the question, as well as the commercial ones, are greater.
This Wikipedia article appears in the latter half of the 1980s column.
Unix history of the 1980s - Wikipedia
By settling AT&T, which had previously been banned from entering the computer field due to a lawsuit against the Antimonopoly Law, at 1983 AT&T started a licensing business using UNIX and banned UNIX from being used without license.After that, Unix became a closed world for a while and Unix culture was on the verge of extinction.That's about it.
Around the same time, standardization activities for Unix systems, which have been divided into various types due to source code distribution and BSD development since the 1970s, have been called the UNIX War, and POSIX by IEEE working group P1003 is one of them.
UNIX War - Wikipedia
Standardized UNIX-Wikipedia
X/Open-Wikipedia
1.Standardization - Think GNU 11th
In the above article, X/Open seems to have started the fastest, but the IEEE working group P1003 seems to have stood up as well.
IEEE working group P1003 1984
While standardization itself is probably an important objective, it's also a great desire to free (or at least) from the constraints of AT&T's licensing business in the name of standardization, and to take the initiative if possible.
It seems that IEEE, a standardization organization, gained the upper hand in the end, not by a group of companies.
Unix History of the 1980s - Wikipedia
The best Unix-related standardization was IEEE POSIX, a compromise between BSD and System V APIs.
Isn't the API defined in posix available in Standard C? has been revised many times in both POSIX and C languages, so it will be important which version and which version you are referring to.
Isn't the current latest version available?
In the first edition of Standard C, in 1988, the first edition of POSIX, the C language was still in the process of standardizing.
ANSI began standardizing C languages in 1983, just before the AT&T dismantlement, but was enacted in 1989, a year after the first POSIX edition.
There is a saying that if you submit it later, it will be possible to reflect it, but since we have been considering the specifications of each independent field for a long time, it will be difficult to deal with them so easily.
With this discussion thread, it seems that some POSIX APIs on the C89 are not supported (or are they being replaced by the language)?
ANSIC89 and POSIX portability?-Slashdot
There were many incompatible implementations of C language itself, so it must have been difficult to consider resolving these differences.
K&R-C Language - Wikipedia
"The C Programming Language," co-authored by Richie and Kahnihan, published in 1978.See then as a substantial C language standard until the standard is established.C is a developable language, and the description in this book did not describe the possible development parts strictly, and there were ambiguous parts.With the spread of C language, many incompatible processing systems were created.This is a common phenomenon in programming languages and is not specific to C language.
Standard C (Standard C)-C Language History of C (History of C)
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