The UNIX® Standard | www.opengroup.org
May 22, 2025 · Single UNIX Specification- “The Standard” The Single UNIX Specification is the standard in which the core interfaces of a UNIX OS are measured. The UNIX standard …
What does the line "#!/bin/sh" mean in a UNIX shell script?
Sep 10, 2011 · When you try to execute a program in unix (one with the executable bit set), the operating system will look at the first few bytes of the file. These form the so-called "magic …
What are the special dollar sign shell variables? - Stack Overflow
Sep 14, 2012 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process …
unix - what does '$?' mean in a shell script? - Stack Overflow
Oct 5, 2012 · I came across a shell script that contains a statement like, if [ $val -eq $? ] What does $? mean here?
linux - Explaining the 'find -mtime' command - Stack Overflow
Sep 1, 2014 · The POSIX specification for find says: -mtime n The primary shall evaluate as true if the file modification time subtracted from the initialization time, divided by 86400 (with any …
unix - How to get PID of process by specifying process name and …
Jul 3, 2013 · pgrep -x <process_name> | xargs kill -9 (incidentally, for this specific use case, might as well do pkill -9 -x <process_name>, but the question asked how to get the PID in general) …
How to check if $? is not equal to zero in unix shell scripting?
How to check if $? is not equal to zero in unix shell scripting? Asked 12 years, 7 months ago Modified 3 years, 7 months ago Viewed 356k times
unix - How to check permissions of a specific directory ... - Stack ...
I know that using ls -l "directory/directory/filename" tells me the permissions of a file. How do I do the same on a directory? I could obviously use ls -l on the directory higher in the hierarchy...
unix - What is the meaning of "POSIX"? - Stack Overflow
Nov 23, 2009 · Since every Unix does things a little differently -- Solaris, Mac OS X, IRIX, BSD, and Linux all have their quirks -- POSIX is especially useful to those in the industry as it …
UNIX® Certification Program | www.opengroup.org
UNIX certification is a trusted and open system industry standard, ensuring that products conform to the most exacting criteria for portability, compatibility, and global interoperability.