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Full Discussion: bash, command line substitution
Top Forums Shell Programming and Scripting bash, command line substitution Post 302555754 by Corona688 on Thursday 15th of September 2011 01:23:18 PM
Old 09-15-2011
Quote:
Originally Posted by skippyV
If we take the above line and paste it "as is" into the call to Script B:
Code:
/home/scriptB.sh  one  two  "th ree"

then the args get separated as desired.
But if we try to configure a variable with the same contents as the above string AND we want the same result:
Code:
/home/scriptB.sh $mystr

then it does not work for me.
Ah. I see now.

The only way to perfectly do what you want is eval, which isn't just awkward, it's dangerous:
Code:
# eval considers a string as its own shell statement, which 
# will process one two "th ree" as three strings as intended.
$ STR='one two "th ree"'
$ eval "printf \"%s\n\" $STR"
one
two
th ree

# But this means it will swallow ANY valid shell syntax, including
# backticks, variable assignments, etc, etc, etc.
# Someone could make your program do anything by feeding
# it the right string.
$ STR='one two "th ree" `touch /`'
$ eval "printf \"%s\n\" $STR"
touch: setting times of `/': Permission denied
one
two
th ree

Why not just use an array in the first place? Much simpler, much safer.
 

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LEARN ABOUT OSX

mac::types

Types(3)						User Contributed Perl Documentation						  Types(3)

NAME

       Mac::Types - Macintosh Toolbox Types and conversions.

DESCRIPTION

       Access to Inside Macintosh is essential for proper use of these functions.  Explanations of terms, processes and procedures are provided
       there.  Any attempt to use these functions without guidance can cause severe errors in your machine, including corruption of data. You have
       been warned.

   Functions
       MacPack [ CONVERTERS ...] CODE, DATA ...
	   Convert a perl value into a Mac toolbox type. Predefined codes are:

	   TEXT
	       Text (an identity operation).

	   enum
	   type
	   keyw
	       A 4-byte string.

	   bool
	       A boolean.

	   shor
	       A short integer.

	   long
	       A long integer.

	   sing
	       A single precision float.

	   doub
	       A double precision float.

	   magn
	       An unsigned long.

	   qdrt
	       A QuickDraw "Rect".

	   'STR '
	       A pascal style string.

	   'STR#'
	       A string list.

	   'fss '
	       A file specification record.

	   You can pass further code mappings as hash references.

       MacUnpack [ CONVERTERS ...] CODE, DATA
	   Convert a Mac toolbox type into a perl value. Predefined codes are as for "MacPack". You can pass further code mappings as hash
	   references.

   XS Functions
       Debugger [ MSG ]
	   Break into MacsBug. Don't use this if you don't know what MacsBug is.

AUTHOR

       Written by Matthias Ulrich Neeracher <neeracher@mac.com>.  Currently maintained by Chris Nandor <pudge@pobox.com>.

perl v5.16.2							    2013-08-25								  Types(3)
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