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Full Discussion: IF statement with square brackets
Top Forums Shell Programming and Scripting IF statement with square brackets Post 302983624 by Don Cragun on Friday 14th of October 2016 03:21:22 AM
Old 10-14-2016
The real question is not what the region is when the code works or fails, but to what do the expansions of the three shell variables: com_dir, dup_file_name_chk, and save_dir expand when the code works and to what do they expand when it fails. One might guess that it is failing when one of those variables contain one or more whitespace characters. One might also guess that the following would also work:
Code:
if [ -f "$com_dir/$dup_file_name_chk" ] || 
[ -f "$save_dir/$dup_file_name_chk" ]
then
.
.
.
fi

You haven't told us what shell you're using, but if [[ expression ]] is working and you're running on AIX, I'll assume you are using ksh or bash. The command:
Code:
[ -f $com_dir/$dup_file_name_chk ]

is a shell built-in utility that performs the same parameter expansion and field splitting that happens whenever the shell evaluates a command line. Without the double quotes surrounding the parameter expansions, if there are whitespace characters in the expansions of those variables, field splitting will cause one or both of those tests to fail. It will also fail if $dup_file_name_chk expands to an empty string. but in that case the double bracket test would also fail.

The command:
Code:
[[ -f $com_dir/$dup_file_name_chk ]]

is part of the syntax of the shell; not a utility. Parameter expansion still occurs in this case, but field splitting does not occur.
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qpaintevent

QPaintEvent(3qt)														  QPaintEvent(3qt)

NAME

       QPaintEvent - Event parameters for paint events

SYNOPSIS

       #include <qevent.h>

       Inherits QEvent.

   Public Members
       QPaintEvent ( const QRegion & paintRegion, bool erased = TRUE )
       QPaintEvent ( const QRect & paintRect, bool erased = TRUE )
       const QRect & rect () const
       const QRegion & region () const
       bool erased () const

DESCRIPTION

       The QPaintEvent class contains event parameters for paint events.

       Paint events are sent to widgets that need to update themselves, for instance when part of a widget is exposed because a covering widget is
       moved.

       The event contains a region() that needs to be updated, and a rect() that is the bounding rectangle of that region. Both are provided
       because many widgets can't make much use of region(), and rect() can be much faster than region().boundingRect(). Painting is clipped to
       region() during processing of a paint event.

       The erased() function returns TRUE if the region() has been cleared to the widget's background (see QWidget::backgroundMode()), and FALSE
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       See also QPainter, QWidget::update(), QWidget::repaint(), QWidget::paintEvent(), QWidget::backgroundMode, QRegion, and Event Classes.

MEMBER FUNCTION DOCUMENTATION

QPaintEvent::QPaintEvent ( const QRegion & paintRegion, bool erased = TRUE )
       Constructs a paint event object with the region that should be updated. The region is given by paintRegion. If erased is TRUE the region
       will be cleared before repainting.

QPaintEvent::QPaintEvent ( const QRect & paintRect, bool erased = TRUE )
       Constructs a paint event object with the rectangle that should be updated. The region is given by paintRect. If erased is TRUE the region
       will be cleared before repainting.

bool QPaintEvent::erased () const
       Returns TRUE if the paint event region (or rectangle) has been erased with the widget's background; otherwise returns FALSE.

const QRect &; QPaintEvent::rect () const
       Returns the rectangle that should be updated.

       See also region() and QPainter::setClipRect().

       Examples:

const QRegion &; QPaintEvent::region () const
       Returns the region that should be updated.

       See also rect() and QPainter::setClipRegion().

       Examples:

SEE ALSO

       http://doc.trolltech.com/qpaintevent.html http://www.trolltech.com/faq/tech.html

COPYRIGHT

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AUTHOR

       Generated automatically from the source code.

BUGS

       If you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html.  Good bug reports help us to help you.
       Thank you.

       The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a
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Trolltech AS							  9 December 2002						  QPaintEvent(3qt)
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