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Full Discussion: bootup sequence
Top Forums UNIX for Dummies Questions & Answers bootup sequence Post 302340894 by Corona688 on Tuesday 4th of August 2009 03:32:20 PM
Old 08-04-2009
Since UNIX covers so many platforms and systems and varieties its hard to give a better than vague answer. But I will bite the bullet and be vague for you.
  • The system automatically loads the bootloader. This is a small program with only one job, to find and load the operating system kernel. On PC's its always in the first sector of the hard drive, or the 'boot' sector.
  • The bootloader loads the kernel into memory and runs it.
  • In linux at least, the first thing the kernel does is detect a whole slew of system parameters and devices. This is similar to the process of loading a driver, except the drivers are built in and just need to be operated.
  • Next, it attempts to mount the root filesystem, since it can't do anything without one.
  • Lastly the kernel creates process number one, init, which runs the processes to prepare the rest of the system and start up all the services its is configured to for its particular runlevel, including all terminal logins etc.
This is the simple way. Sometimes instead of a root filesystem, the bootloader gives the kernel a glob of memory containing files loaded from disk, which it may use to load extra drivers etc. before it mounts the real root filesystem overtop of it.
 

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LEARN ABOUT REDHAT

tcl_backslash

Tcl_Backslash(3)                                              Tcl Library Procedures                                              Tcl_Backslash(3)

__________________________________________________________________________________________________________________________________________________

NAME

       Tcl_Backslash - parse a backslash sequence

SYNOPSIS

       #include <tcl.h>

       char
       Tcl_Backslash(src, countPtr)

ARGUMENTS

       char *src (in)               Pointer to a string starting with a backslash.

       int *countPtr (out)          If countPtr is not NULL, *countPtr gets filled in with number of characters in the backslash sequence, includ-
                                    ing the backslash character.
_________________________________________________________________

DESCRIPTION

       The use of Tcl_Backslash is deprecated in favor of Tcl_UtfBackslash.

       This is a utility procedure provided for backwards compatibility with non-internationalized Tcl extensions.  It parses a backslash sequence
       and returns the low byte of the Unicode character corresponding to the sequence.  Tcl_Backslash modifies *countPtr to contain the number of
       characters in the backslash sequence.

       See the Tcl manual entry for information on the valid backslash sequences.  All of the sequences described in the Tcl manual entry are sup-
       ported by Tcl_Backslash.

SEE ALSO

       Tcl(n), Tcl_UtfBackslash(3)

KEYWORDS

       backslash, parse

Tcl                                                                     8.1                                                       Tcl_Backslash(3)
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