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Full Discussion: bash shell: 'exec', 'eval', 'source' - looking for help to understand
Top Forums Shell Programming and Scripting bash shell: 'exec', 'eval', 'source' - looking for help to understand Post 302169863 by alex_5161 on Friday 22nd of February 2008 03:37:57 PM
Old 02-22-2008
jim mcnamara -
thank you, very much, everything clear and usefull for me now!

I am realy exiting to understand it. Now I have new (for me ) possibility in scripting and in shell.
Definetely, 'eval' gives usefull opportunity!
The 'exec' - nice to know that and it is good to use it, too.
The 'sorce' - it appeared that I have used it already for long time (as '. script') but did not realized tha all definishions of the curent shell are available in runing script by that (other part - backward - usualy is a reason to use the '. scr')
I've just tryed it and maybe it would be usefull to show it here, too, although your explanation pretty enough, but, anyway, here it is:

Code:
bash-802:/home/dca0701/develop/src> cat > try.sh
/usr/bin/echo "\n -- try to use already defined in shell alias:"
ec "<<< this printed by shell alias 'ec'"

shopt -s expand_aliases
alias ec2=ec
ec "--- new alias is declared as ec2"
^C
bash-803:/home/dca0701/develop/src>
bash-803:/home/dca0701/develop/src> chmod 777 try.sh
bash-804:/home/dca0701/develop/src>
bash-804:/home/dca0701/develop/src>
bash-804:/home/dca0701/develop/src> try.sh

 -- try to use already defined in shell alias:
./try.sh: ec: command not found
./try.sh: ec: command not found
bash-805:/home/dca0701/develop/src>
bash-805:/home/dca0701/develop/src> source try.sh

 -- try to use already defined in shell alias:
<<< this printed by shell alias 'ec'
--- new alias is declared as ec2
bash-806:/home/dca0701/develop/src> ec2 hello
hello
bash-807:/home/dca0701/develop/src>

Once again, thank you very much!
 

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LEARN ABOUT OPENSOLARIS

shells

shells(4)							   File Formats 							 shells(4)

NAME

       shells - shell database

SYNOPSIS

       /etc/shells

DESCRIPTION

       The shells file contains a list of the shells on the system. Applications use this file to determine whether a shell is valid. See getuser-
       shell(3C). For each shell a single line should be present, consisting of the shell's path, relative to root.

       A hash mark (#) indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by  the  routines
       which search the file. Blank lines are also ignored.

       The following default shells are used by utilities: /bin/bash, /bin/csh, /bin/jsh, /bin/ksh, /bin/ksh93, /bin/pfcsh, /bin/pfksh, /bin/pfsh,
       /bin/sh, /bin/tcsh, /bin/zsh, /sbin/jsh, /sbin/sh, /usr/bin/bash, /usr/bin/csh, /usr/bin/jsh, /usr/bin/ksh, /usr/bin/ksh93, /usr/bin/pfcsh,
       /usr/bin/pfksh, /usr/bin/pfsh, and /usr/bin/sh, /usr/bin/tcsh, /usr/bin/zsh, and /usr/sfw/bin/zsh. /etc/shells overrides the default list.

       Invalid shells in /etc/shells could cause unexpected behavior, such as being unable to log in by way of ftp(1).

FILES

       /etc/shells    list of shells on system

SEE ALSO

       vipw(1B), ftpd(1M), sendmail(1M), getusershell(3C), aliases(4)

SunOS 5.11							    20 Nov 2007 							 shells(4)
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