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Full Discussion: Retaining value outside loop
Top Forums Shell Programming and Scripting Retaining value outside loop Post 303031493 by MadeInGermany on Friday 1st of March 2019 09:31:15 AM
Old 03-01-2019
A correction:
Code:
i=1
while [ i -le 100 ] ; do
  (( i += 1 ))
done
print $i

produces 101 in ksh and errors in Bourne shell.
While the following
Code:
i=1
while [ $i -le 100 ] ; do
  i=`expr $i + 1`
done
echo $i

runs on both,
but might produce 1 in an old Bourne shell because it always runs the while loop in a sub shell.
A later Bourne shell has got a fix, but seeing a redirection it still runs the sub shell.
Code:
i=1
while [ $i -le 100 ] ; do
  i=`expr $i + 1`
done </dev/null
echo $i

That means all Bourne shells do not work with the previously suggested <<EOF redirection.
The Posix shell has got it all fixed. And all Posix-compatible shells.
But a pipe really forces a sub shell. Because it is the last part of the pipe. Compare with a simple command
Code:
echo "a:b:c:" | IFS=":" read a b c

Only the ksh has got the (incompatible) modification to run the last part of the pipe in the current shell.

Back to the initial post - that works only in ksh.
The following is portable to all Posix-compatible shells:
Code:
totalstr=$(
# sub shell starts
  sep=""
  echo "$loc" |
  while IFS= read -r line ; do
    # the pipe might force a sub sub shell
    printf "%s" "$sep$line"
    sep=","
  done
# sub shell ends
)
echo "Final Output:$totalstr "

As you can see, a sub shell inherits everything from the current shell, but not vice versa.
 

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RESIZE(1)                                                     General Commands Manual                                                    RESIZE(1)

NAME
resize - set environment and terminal settings to current xterm window size SYNOPSIS
resize [ -u | -c ] [ -s [ row col ] ] DESCRIPTION
Resize prints a shell command for setting the appropriate environment variables to indicate the current size of xterm window from which the command is run. For this output to take effect, resize must either be evaluated as part of the command line (usually done with a shell alias or function) or else redirected to a file which can then be read in. From the C shell (usually known as /bin/csh), the following alias could be defined in the user's .cshrc: % alias rs 'set noglob; eval `resize`' After resizing the window, the user would type: % rs Users of versions of the Bourne shell (usually known as /bin/sh) that don't have command functions will need to send the output to a tempo- rary file and then read it back in with the "." command: $ resize > /tmp/out $ . /tmp/out Resize determines the user's current shell by first checking if $SHELL is set, and using that. Otherwise it determines the user's shell by looking in the password file. Generally Bourne-shell variants (including ksh) do not modify $SHELL, so it is possible for resize to be confused if one runs resize from a Bourne shell spawned from a C shell. OPTIONS
The following options may be used with resize: -u This option indicates that Bourne shell commands should be generated even if the user's current shell isn't /bin/sh. -c This option indicates that C shell commands should be generated even if the user's current shell isn't /bin/csh. -s [rows columns] This option indicates that Sun console escape sequences will be used instead of the VT100-style xterm escape codes. If rows and columns are given, resize will ask the xterm to resize itself. However, the window manager may choose to disallow the change. Note that the Sun console escape sequences are recognized by XFree86 xterm and by dtterm. The resize program may be installed as sunsize, which causes makes it assume the -s option. The rows and columns arguments must appear last; though they are normally associated with the -s option, they are parsed separately. FILES
/etc/termcap for the base termcap entry to modify. ~/.cshrc user's alias for the command. ENVIRONMENT
TERM set to "xterm" if not already set. TERMCAP variable set on systems using termcap COLUMNS, LINES variables set on systems using terminfo SEE ALSO
csh(1), tset(1), xterm(1) AUTHORS
Mark Vandevoorde (MIT-Athena), Edward Moy (Berkeley) Copyright (c) 1984, 1985 by X Consortium See X(7) for a complete copyright notice. X Window System RESIZE(1)
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