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Full Discussion: Variables scope.
Top Forums Shell Programming and Scripting Variables scope. Post 302226574 by fpmurphy on Tuesday 19th of August 2008 09:05:29 AM
Old 08-19-2008
Setting FLAG within a while loop works in bash, ksh, ash, zsh. It does not work in sh (Bourne shell) because redirection causes a subshell. From the sh(1) manpage on Solaris.
Quote:
If the input or the output of a while or until loop is
redirected, the commands in the loop are run in a sub-shell,
and variables set or changed there have no effect on the
parent process:

lastline=
while read line
do

lastline=$line
done < /etc/passwd
echo "lastline=$lastline" # lastline is empty!
 

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break(1)                                                           User Commands                                                          break(1)

NAME
break, continue - shell built-in functions to escape from or advance within a controlling while, for, foreach, or until loop SYNOPSIS
sh break [n] continue [n] csh break continue ksh *break [n] *continue [n] DESCRIPTION
sh The break utility exits from the enclosing for or while loop, if any. If n is specified, break n levels. The continue utility resumes the next iteration of the enclosing for or while loop. If n is specified, resume at the n-th enclosing loop. csh The break utility resumes execution after the end of the nearest enclosing foreach or while loop. The remaining commands on the current line are executed. This allows multilevel breaks to be written as a list of break commands, all on one line. The continue utility continues execution of the next iteration of the nearest enclosing while or foreach loop. ksh The break utility exits from the enclosed for, while, until, or select loop, if any. If n is specified, then break n levels. If n is greater than the number of enclosing loops, the outermost enclosing loop shall be exited. The continue utility resumes the next iteration of the enclosed for, while, until, or select loop. If n is specified then resume at the n- th enclosed loop. If n is greater than the number of enclosing loops, the outermost enclosing loop shall be used. 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 that follow 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 also that word splitting and file name genera- tion are not performed. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), exit(1), ksh(1), sh( 1), attributes(5) SunOS 5.10 17 Jul 2002 break(1)
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