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Full Discussion: Positional Parameters Arguments/Variables when using dot (.)
Top Forums UNIX for Beginners Questions & Answers Positional Parameters Arguments/Variables when using dot (.) Post 303039558 by wisecracker on Wednesday 9th of October 2019 09:59:46 AM
Old 10-09-2019
I am at a loss as to what you are trying to do.
IF you are sourcing a file, . /path/to/file then that will execute inside the parent shell.
Variables will be passed at that position where the sourced file is...
A quick demo...
Sourced file:
Code:
#!/bin/sh
# Test file to be sourced.

MYVAR=$1

echo "Inside source file \${MYVAR} = ${MYVAR}"

AND parent file:
Code:
#!/bin/sh
# Parent test file...

# Sourced file in the same directory.
. ./source_file.sh 'UNIX'

echo "Sourced file \${MYVAR} = ${MYVAR}"

MYVAR="Bazza"

echo "Parent file \${MYVAR} = ${MYVAR}"

. ./source_file.sh 'LINUX'

echo "Sourced file \${MYVAR} = ${MYVAR}"

Results OSX 10.14.6, default shell terminal.
Code:
Last login: Wed Oct  9 14:38:32 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> chmod 755 parent_file.sh
AMIGA:amiga~/Desktop/Code/Shell> chmod 755 source_file.sh
AMIGA:amiga~/Desktop/Code/Shell> ./parent_file.sh
Inside source file ${MYVAR} = UNIX
Sourced file ${MYVAR} = UNIX
Parent file ${MYVAR} = Bazza
Inside source file ${MYVAR} = LINUX
Sourced file ${MYVAR} = LINUX
AMIGA:amiga~/Desktop/Code/Shell> _

 

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LEARN ABOUT POSIX

shift

SHIFT(1P)						     POSIX Programmer's Manual							 SHIFT(1P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       shift -- shift positional parameters

SYNOPSIS

       shift [n]

DESCRIPTION

       The positional parameters shall be shifted. Positional parameter 1 shall be assigned the value of parameter (1+n),  parameter  2  shall	be
       assigned  the  value of parameter (2+n), and so on. The parameters represented by the numbers "$#" down to "$#-n+1" shall be unset, and the
       parameter '#' is updated to reflect the new number of positional parameters.

       The value n shall be an unsigned decimal integer less than or equal to the value of the special parameter '#'.  If n is not given, it shall
       be assumed to be 1. If n is 0, the positional and special parameters are not changed.

OPTIONS

       None.

OPERANDS

       See the DESCRIPTION.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       None.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       Not used.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       If  the	n  operand  is invalid or is greater than "$#", this may be considered a syntax error and a non-interactive shell may exit; if the
       shell does not exit in this case, a non-zero exit status shall be returned. Otherwise, zero shall be returned.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       None.

EXAMPLES

       $ set a b c d e
       $ shift 2
       $ echo $*
       c d e

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.14, Special Built-In Utilities

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
       ogy  --	Portable  Operating  System  Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
       event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Stan-
       dard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE
/The Open Group						       2013								 SHIFT(1P)
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