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Full Discussion: Unfamiliar array syntax
Top Forums Shell Programming and Scripting Unfamiliar array syntax Post 302453887 by Scrutinizer on Thursday 16th of September 2010 05:07:34 PM
Old 09-16-2010
This is construction that is used if a shell in question does not know arrays. The way it is used in the script that you were handed, is a bit cumbersome. Instead of
Code:
backup_host=`eval echo \\$collect${N}_backup_host`

this could be used:
Code:
eval backup_host=\$collect${N}_backup_host

eval works like this: first everything after eval is passed as parameter to eval. The shell processes the variable ${N}. The first $ is escaped ( \$ ), so that it is not treated as a special character. So after processing the command eval gets the following string (suppose N=1):
Code:
backup_host=$collect1_backup_host

end then executes this. As a result you would get:
Code:
$ N=1
$ eval backup_host=\$collect${N}_backup_host
$ echo $backup_host
alt-host.xxx.net


Last edited by Scrutinizer; 09-16-2010 at 06:32 PM..
 

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DH_INSTALLDEBCONF(1)						     Debhelper						      DH_INSTALLDEBCONF(1)

NAME
dh_installdebconf - install files used by debconf in package build directories SYNOPSIS
dh_installdebconf [debhelperoptions] [-n] [--params] DESCRIPTION
dh_installdebconf is a debhelper program that is responsible for installing files used by debconf into package build directories. It also automatically generates the postrm commands needed to interface with debconf. The commands are added to the maintainer scripts by dh_installdeb. See dh_installdeb(1) for an explanation of how that works. Note that if you use debconf, your package probably needs to depend on it (it will be added to ${misc:Depends} by this program). Note that for your config script to be called by dpkg, your postinst needs to source debconf's confmodule. dh_installdebconf does not install this statement into the postinst automatically as it is too hard to do it right. FILES
debian/package.config This is the debconf config script, and is installed into the DEBIAN directory in the package build directory. Inside the script, the token #DEBHELPER# is replaced with shell script snippets generated by other debhelper commands. debian/package.templates This is the debconf templates file, and is installed into the DEBIAN directory in the package build directory. debian/po/ If this directory is present, this program will automatically use po2debconf(1) to generate merged templates files that include the translations from there. For this to work, your package should build-depend on po-debconf. OPTIONS
-n, --no-scripts Do not modify postrm script. -- params Pass the params to po2debconf. SEE ALSO
debhelper(7) This program is a part of debhelper. AUTHOR
Joey Hess <joeyh@debian.org> 11.1.6ubuntu2 2018-05-10 DH_INSTALLDEBCONF(1)
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