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POSIX Way to Check User Input in Shell Scripts

This post discusses how to validate both localized and non-localized user input in the POSIX shell.

June 15th, 2018 | Tags: , , , , , , , , | Category: bash, Linux, Localization, POSIX, REGEX, shell | Comments are closed

On-disk File Timestamps

The Single Unix Specification, Base Definitions (XBD), Section 4.8 entitled “File Times Update” states “An implementation may update timestamps that are marked for update immediately, or it may update such timestamps periodically.” This means that, for example, that file read and write operations are free to set the appropriate flags in the in-memory structures and do the actual updating of the on-disk filesystem structures at a later time. Assuming periodically means from time to time, it implies that a POSIX-compliant operating system is free to update it’s on-disk structures when it is convenient for the operating system to do so.

July 13th, 2015 | Tags: , , , | Category: kernel, Security, Unix | Comments are closed

IEEE Std. 1003.1-2008

I am a big fan of the POSIX.1 standard.  The lastest version of this standard (IEEE Std. 1003.1-2008) was released in December 1st 2008.  The formal name for this version of the standard is Portable Operating System Interface (POSIX) Base Specifications, Issue 7. Like its predecessors, IEEE Std. 1003.1-2004 and IEEE Std. 1003.1-2001, it was developed by the Austin Common Standards Revision Group (CSRG), more commonly called the Austin Working Group, which is a joint technical working group established in 1999 to develop and maintain the core open systems interfaces.  The working group’s stated approach to specification development is write

January 1st, 2009 | Tags: | Category: IEEE 1003.1, POSIX, The Open Group | Comments are closed