POSIX is an acronym for "Portable Operating System Interface", a family of standards specified by the IEEE for maintaining compatibility between operating systems.

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Threads vs interrupts

What does it mean when threads are time-sliced? Does that mean they work as interrupts, don't exit while routine is not finished? Or it executes one instruction from one thread then one instruction ...
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164 views

How to send all output to `logger` in POSIX shell?

I'd like to log standard output and standard error separately in .xprofile using logger. In Bash I think that would look something like this: exec 1> >(logger --priority user.notice --tag ...
2
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1answer
101 views

fgrep or grep -F, which one is better for portable script? [closed]

I am having this controversial commentary on this answer to a quesion whether we should use fgrep or grep with the -F switch (i.e grep -F) for portability. The points that have been came into light so ...
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Linux: POSIX Timers ignore Thread Priority [migrated]

I have a Thread which has to run every millisecond. When no other thread of the program is active, everything is fine. But if more than 3 other threads are running, the Timer-Thread is only called ...
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1answer
30 views

Compiling Python 2.7.10 Error

I want to add Python 2.7 to my Unix. I downloaded the sources to the VirtualBox on which the Unix is installed and run ./configure --prefix=/usr \ --enable-shared \ ...
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1answer
17 views

ipcs(1) POSIX equivalent to System V

I know that with ipcs(1) command, one can monitor System V message queues, shared memory and semaphores, but how do I monitor POSIX message queues, shared memory and semaphores. For POSIX message ...
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4k views

Why are UNIX/POSIX system call namings so illegible?

What is the reason to use such untelling system call names like time and creat instead of getCurrentTimeSecs and createFile or, maybe more suitable on Unix get_current_time_secs and create_file. Which ...
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1answer
52 views

/bin/sh script error “arithmetic expression: expecting primary: ” + “ ”

ERROR: ./client-disconnect.sh: 22: ./client-disconnect.sh: arithmetic expression: expecting primary: " + " I just need to know how to fix it. It's for user accounting with OpenVPN. Script ...
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27 views

Getting CRC mismatch warnings in gdb on cygwin

When I run any program under gdb in cygwin shell I get following warnings... warning: the debug information found in "/usr/lib/debug//usr/bin/cyggcc_s-seh-1.dll.dbg" does not match ...
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1answer
91 views

Is there a command line tool to manage unix signals?

Is there a command runner like env, nice, nohup, etc., that can run a program with modified signals? In my case, I need something to reset SIGINT to SIG_DFL. Why do I need this? Because ...
8
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1answer
199 views

What is the point of using multiple exclamation marks in sed?

POSIX sed documentation said: A function can be preceded by one or more '!' characters, in which case the function shall be applied if the addresses do not select the pattern space. Zero or ...
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2answers
50 views

Grep for regex in basename but return wholename

So say I have a list of files in a text file: ... /foo/barfoo /bar/foo/foobar /foobar/bar/foo ... I have a script that will search through this text file and, much like the locate command, I want ...
4
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1answer
39 views

Posix command that moves cursor to specific position in terminal window

in school we have been assigned a homework in which we are suppose to print an ascii art into a terminal window. A input is data in format [x_coordinate, y_coordinate, char_ascii_value] (there is no ...
2
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1answer
55 views

POSIX shell scripting and performance tuning [closed]

Nowadays, I'm researching for performance tuning for shell scripting , And I have been prevented to POSIX shell scripting, However it's only a standard, But I think it's rathar than standard for do ...
4
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1answer
58 views

What are the 'n', 'l', '3pm' sections of the manual for?

An excerpt from the man man page: The default action is to search in all of the available sections following a pre-defined order ("1 n l 8 3 2 3posix 3pm 3perl 5 4 9 6 7" by default) What are ...
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1answer
35 views

read reading input devided by spaces

How can I read in POSIX bash input like this: <name>,<tag1> <tag2> <tag3>… I tried while read line;do done but this wants newlines, all I have is spaces. (Is IFS solution? ...
2
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1answer
94 views

uname -n vs hostname

What is the difference between uname -n and hostname? Are there any real differences in what they return? Are there any differences in availability on different OSes? Is one of them included in POSIX ...
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3answers
65 views

When to use XPG* version of a command?

I occasionally do work on an older Solaris machine whose default version of grep is non-POSIX-compliant. This causes problems in my rc files because the default grep on the machine doesn't support ...
2
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1answer
76 views

I have a multi-line string that I need to iterate over, but I'm not using bash. Advice?

I'm using Dash because this is to run on my rPi. Bash is not an option. I'm rewriting a Bash script to work with Dash. I'm hoping to make it as POSIX-compliant (portable) as possible. The thing is ...
2
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1answer
58 views

Order between options and operands?

When using a utility program, we may specify options (and their option arguments) and/or operands. In most cases (in the sense of conforming to some standard (POSIX?)) does the order between ...
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1answer
94 views

Will `mv` ever have the ability to create directories?

This question asks for the best way to create a directory when using mv if it doesn't exist. My question is why isn't this an inbuilt feature of mv? Is there some fundamental reason due to which this ...
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1answer
93 views

Multithreading in Mail server (Postfix)

I need to perform multithreading on postfix mail server. I read about POSIX multithreading but could it be linked to postfix smtp server and if yes then how? System Specification: ubuntu 14.04 LTS and ...
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1answer
66 views

What, as examples, can produce a POLLNVAL?

The reference about poll() just says “The specified fd value is invalid. This flag is only valid in the revents member; it shall ignored in the events member.”. That's not clear (at least to me): if ...
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59 views

find printf switch POSIX alternative

I'd like to rewrite these 2 command so they will use only POSIX-complaint switches: find "$TARGET_DIR" -maxdepth 1 -type d -printf '(DIR) %f\n' find "$TARGET_DIR" -maxdepth 1 -type f -printf '%s %f ...
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OS X Yosemite is SUS - Single Unix Specification 3 certified. But what posix standard is it compliant to? the latest one is 2008

I'm confused. Is SUS compliance the same as POSIX compliance? Is yosemite compliant to the latest standards, what years exactly?
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4answers
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Use #!/bin/sh or #!/bin/bash for Ubuntu-OSX compatibility and ease of use & POSIX

I know that I can use either as the first line of scripts to invoke the desired shell. Would #!/bin/sh be recommended if compatibility with all unix systems is an absolute requirement? In my case ...
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44 views

POSIX description of cp -R

I just became really confused by the implementation of bash's cp -R command compared to how POSIX words what should happen Given the posix definition, I would expect cp -R srcDir existingDestDir to ...
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1answer
161 views

Why does 'find -exec cmd {} +' need to end in '{} +'?

Preface: I understand the difference between -exec {} \; & -exec {} +. I also don't have a problem as such, I am just curious about the semantics of find. When ending the -exec argument with + ...
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1answer
38 views

Is field splitting and filename expansion turn off in RHS of variable assignment portable?

In most POSIX compliant shell like bash. ksh, dash, mksh, pdksh, when variable assignment occur, field splitting and filename expansion (and brace expansion if the shell supports) are not performed in ...
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1answer
170 views

Regular expression in unzip files argument not working

I'm trying to view the contents of a zip archive using an extremely simple regular expression. This works: rmorton@Rockette:~$ unzip -l Downloads/WeiDU-Linux-236.zip "*/i386/tolower" "*/i386/weidu" ...
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7answers
2k views

Is test or [ or [[ more portable both between bash shells and between other shells?

I see I can do $ [ -w /home/durrantm ] && echo "writable" writable or $ test -w /home/durrantm && echo "writable" writable or $ [[ -w /home/durrantm ]] && echo ...
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1answer
219 views

open() return new file descriptor posix [closed]

I have to set the return values for open() in posix. How do I return "the new file descriptor" as it is said in the Linux man pages: RETURN VALUE open(), openat(), and creat() return the new ...
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2answers
367 views

Is there a specific reason why iptables would return an exit code of 3 (instead of 1?) when executed without sufficient privileges?

I simply forgot to use sudo: usr@arch ~[0] $ iptables -L iptables v1.4.21: can't initialize iptables table `filter': Permission denied (you must be root) Perhaps iptables or your kernel needs to be ...
3
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2answers
58 views

How is it possible to execute a command with an unknown number of arguments in a POSIX shell?

I want to search for multiple words inside the current directory. To accomplish this I use something like this. grep -e "word1" -e "word2" -R . This works fine. Taking this one step further, I ...
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1answer
110 views

Single or double brackets and portability

I have found some very good answers here on the differences between [ and [[ in 'if' statements. For specific named shells, it seems to be a good idea to use [[ over [ (and it is faster, too). I'm ...
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1answer
668 views

Consequences of setting up POSIX locales

Small background of the situation: We are using several UBUNTU servers having English as working language; however having en_US locale set in machines we encounter problems with apt-cacher-ng ...
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1answer
113 views

Process IDs range

On GNU/Linux system I seen only positive PIDs, but when kernel panic occured I seen info about process with PID=0. What's it? On Minix 3 I seen processes with negative PIDs. Minix is POSIX-compatible ...
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1answer
310 views

regarding portable sed -e… d b or ! b?

In this edit Stéphane Chazelas POSIXifies (again) my sed formatting by inserting an -expression break and another -expression statement. Now, I might just ask him why in the comments, I suppose, but ...
25
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1answer
1k views

When and how was the double-dash (--) introduced as an end of options delimiter in Unix/Linux?

I don't think the shell/utilities in historical Unix nor in something as "recent" as 4.4BSD supported using a double-dash(or two consecutive hyphens) as an end of options delimiter. With FreeBSD, you ...
3
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3answers
242 views

Interactive command usage reference: do you generally have that on Unix?

The question of why some commands rely on manpages whereas others rely on something like the --help flag for providing command usage reference is not new. There is usually a difference in scope ...
6
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1answer
228 views

Does Posix require any devices?

Does Posix require any devices? For example, /dev/urandom, /dev/zero or /dev/null? I suspect not because of non-*nix OSes, but wanted to ask for completeness.
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1answer
827 views

Removing non-printable characters using POSIX sed

Files created with roff and other "old-school" tools (for example man pages on many Unix systems) generate bold and underlined text in minimalistic terminals using tricks involving non-printable ASCII ...
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3answers
428 views

`/proc/$PID/cwd` : is there a POSIX equivalent?

Linux has a /proc directory and file‑system, which as far as I can tell, is not part of POSIX. In each /proc/$PID subdirectories, is a symbolic link, cwd, pointing to the actual working directory of ...
3
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1answer
4k views

How do I use grep to find a text string in files in sub folders of a parent folder without -r switch

I'm using Solaris 10 and have two grep versions one in /usr/bin and one in /usr/xpg4/bin. I have been searching for an answer on how to search for text within files within sub folders of a parent ...
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7answers
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What's the difference of the Userland vs the Kernel?

I am trying to understand exactly what is userland? everyone that I ask says: "Anything that is not kernel". but it is not tangible for me. When I am reading that kernel can run that driver on the ...
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4answers
228 views

Protected environment variables?

Are there names of environment variables that cannot be overwritten by the user/a call to setenv? As I understand from POSIX1.2008, any process may edit the environment block, but must avoid ...
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2answers
555 views

explanation on chown(1) POSIX spec

The POSIX spec for the chown utility mentions in its rationale section about the chown user:group syntax (formerly chown user.group) (emphasis mine): The 4.3 BSD method of specifying both owner ...
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2answers
292 views

How exactly does `if $cmd ; then $cmd ; fi` differ from `$cmd && $cmd`?

In an answer to another very good question I made the following assertion: According to my reading of the POSIX specs, the use of one or the other makes no difference from a parsing standpoint. ...
2
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2answers
156 views

bash completion in Posix mode

I would like to use an interactive Posix bash shell but the autocomplete feature doesn't work. When I type the Tab character it simply prints a tab. The tab completion works only when I'm in a ...
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1answer
377 views

bash completion on posix mode [duplicate]

I would like to use an interactive posix bash shell but the autocompletion feature doesn't work. When i type the tab character it simply prints a tab. The tab completion only works when i'm on a non ...