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Full Discussion: Input redirection within bash script
Top Forums Shell Programming and Scripting Input redirection within bash script Post 302994231 by Aia on Monday 20th of March 2017 03:15:01 PM
Old 03-20-2017
Quote:
Originally Posted by heinzel
Hi,

when I try to redirect input and the command is described as a string within an array redirection does not work. why?

Code:
#!/bin/bash

dir=("tail < ./hello.txt")

tail < ./hello.txt #works
${dir[0]} #does not work

dir=("tail < ./hello.txt") is the equivalent of dir="tail < ./hello.txt"
You are assigning a string to a variable.
echo $dir will show you the string tail < ./hello.txt and not the execution of the command.

By the way, you do not need redirection. tail can read from the file without extra help as tail hello.txt

dir=$(tail hello.txt) will assign the result of executing the command into the variable dir.

Code:
dir="tail hello.txt"
eval $dir

That will evaluate the string tail hello.txt as a command.
Therefore,
eval ${dir[0]} will do the same.
This User Gave Thanks to Aia For This Post:
heinzel
 

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LEARN ABOUT REDHAT

xmscrollvisible

XmScrollVisible(library call)											     XmScrollVisible(library call)

NAME

       XmScrollVisible -- A ScrolledWindow function that makes an invisible
	descendant of a ScrolledWindow work area visible

SYNOPSIS

       #include <Xm/ScrolledW.h>
       void XmScrollVisible(
       Widget scrollw_widget,
       Widget widget,
       Dimension left_right_margin,
       Dimension top_bottom_margin);

DESCRIPTION

       XmScrollVisible makes an obscured or partially obscured widget or gadget descendant of a ScrolledWindow work area visible. The function re-
       positions the work area and sets the specified margins between the widget and the nearest viewport boundary. The widget's location relative
       to  the	viewport determines whether one or both of the margins must be adjusted. This function requires that the XmNscrollingPolicy of the
       ScrolledWindow widget be set to XmAUTOMATIC.

       scrollw_widget
		 Specifies the ID of the ScrolledWindow widget whose work area window contains an obscured descendant.

       widget	 Specifies the ID of the widget to be made visible.

       left_right_margin
		 Specifies the margin to establish between the left or right edge of the widget and the associated edge  of  the  viewport.   This
		 margin is established only if the widget must be moved horizontally to make it visible.

       top_bottom_margin
		 Specifies  the  margin  to  establish between the top or bottom edge of the widget and the associated edge of the viewport.  This
		 margin is established only if the widget must be moved vertically to make it visible.

       For a complete definition of ScrolledWindow and its associated resources, see XmScrolledWindow(3)

RELATED

       XmScrolledWindow(3).

														     XmScrollVisible(library call)
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