Bash IFS Post: 302697337

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Top Forums Shell Programming and Scripting Bash IFS Post 302697337 by kristinu on Thursday 6th of September 2012 03:06:15 PM

09-06-2012

Registered User

There is another thing I am unsure about. It is when I am resetting IFS. My dilemma is what happens when I use the code I attached and the following

Code:

OLDIFS="$IFS"
IFS="|="                # IFS controls splitting. Split on "|" and "="
set -- $*               # Set the positional parameters to the command line arguments.

narg="$#"

while [ "$#" -gt 0 ]
do

  case "$1" in

  # name of output segy file
  "--ofl")
    shift
    val_ofl="${1}"
    hasArg_ofl="true"
  ;;

  # number ot time samples
  "--nt")
    shift
    val_nt="${1}"
    hasArg_nt="true"
  ;;

  # x-positions of sources
  "--xsrc")
    shift
    val_xSrc="${1}"
    hasArg_xSrc="true"
  ;;

  *)
    value_errLst="$arg_errLst ${1}"
    hasArg_errLst="true"
  ;;

  esac

  shift                 # Skip ahead to the next argument

done

IFS="$OLDIFS"

---------- Post updated at 02:06 PM ---------- Previous update was at 02:01 PM ----------

Originally my thinking was to reset IFS after the while (after processing all arguments). However, doing

Code:

OLDIFS="$IFS"
IFS="|="                # IFS controls splitting. Split on "|" and "="
set -- $*               # Set the positional parameters to the command line arg$
IFS="$OLDIFS"

while [ "$#" -gt 0 ]
do

...

does not seem to pose problems. What's happening?

kristinu

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LEARN ABOUT X11R4

shift

shift(1)							   User Commands							  shift(1)

NAME

       shift - shell built-in function to traverse either a shell's argument list or a list of field-separated words

SYNOPSIS

   sh
       shift [n]

   csh
       shift [variable]

   ksh
       * shift [n]

DESCRIPTION

   sh
       The positional parameters from $n+1 ... are renamed $1 ... . If n is not given, it is assumed to be 1.

   csh
       The  components of argv, or variable, if supplied, are shifted to the left, discarding the first component. It is an error for the variable
       not to be set or to have a null value.

   ksh
       The positional parameters from $n+1 $n+1 ... are renamed $1 ..., default n is 1. The parameter n can  be  any  arithmetic  expression  that
       evaluates to a non-negative number less than or equal to $#.

       On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

       1.  Variable assignment lists preceding the command remain in effect when the command completes.

       2.  I/O redirections are processed after variable assignments.

       3.  Errors cause a script that contains them to abort.

       4.  Words,  following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
	   able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation  are  not
	   performed.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       csh(1), ksh(1), sh(1), attributes(5)

SunOS 5.10							    15 Apr 1994 							  shift(1)

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