I have made a simple script to find all programs that use a tcp wrapper, it will supply a reasonable default for my system if none is given.
After some digging I realized that the expansion operators pass their default return value single quoted (according to bash -x trace). I have wildcard expansions in my return value, and it works if used with eval.
Its working perfect with eval, but I don't know why.
Code:
#! /bin/bash
ldd_path="$*"
while read line
do
if [[ "$line" =~ ^/.*:$ ]]
then
current_binary="$line"
elif [[ "$line" =~ .*libwrap.so.0.* ]]
then
printf '%s\n' "$current_binary"
fi
done < <(eval ldd ${ldd_path:-"/usr/bin/* /usr/sbin/*"})
My question is really how is eval working with wildcards if they are passed with single quotes, bash -x shows eval working on this:
Code:
eval ldd '/usr/bin/* /usr/sbin/*'
I though evaluation order will prevent this from working but it is.
Hi,
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A = "(5*2)-1" (this equation is read from a file and varies line by line)
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cmd = "awk 'BEGIN{print "A"}'"
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Hi -
I have an expression that evaluates to "Alive" or some other condition. e.g. if I run :-
awk -F \| '{gsub(/]*/,"",$4); print $4 }'
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Hello guys,
I'm actually working on my master thesis which has for subject the evaluation of virtual firewall in a cloud environment. To do so, I installed my own cloud using OpenNebula (as a frontend) and Xen (as a Node) on two different machines. The Xen machine is my virtual firewall thanks... (2 Replies)
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I have made a simple script to find all programs that use a tcp wrapper, it will supply a reasonable default for my system if none is given.
After some digging I realized that the expansion operators pass their default return value single quoted (according to bash -x trace). I have wildcard... (2 Replies)
Could somebody please explain to me why and how the highlighted line(s) (?) of code puts the "test" evaluation into "result" and then to $enable_static ? Or does not ?
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Discussion started by: anne
3 Replies
LEARN ABOUT HPUX
libbash
LIBBASH(7) libbash Manual LIBBASH(7)NAME
libbash -- A bash shared libraries package.
DESCRIPTION
libbash is a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
want to load and use in scripts of your own.
It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.
Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1). A bash shared library that can be loaded
using
ldbash(1) must answer 4 requirments:
1. It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).
2. It must contain a line that begins with '#EXPORT='. That line will contain (after the '=') a list of functions that the library
exports. I.e. all the function that will be usable after loading that library will be listed in that line.
3. It must contain a line that begins with '#REQUIRE='. That line will contain (after the '=') a list of bash libraries that are
required for our library. I.e. every bash library that is in use in our bash library must be listed there.
4. The library must be listed (For more information, see ldbashconfig(8)).
Basic guidelines for writing library of your own:
1. Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.
2. Try to declare all variables intended for internal use as local.
3. Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
__<library_name>_
For example, internal function myfoosort of hashstash library should be named as
__hashstash_myfoosort
This helps to avoid conflicts in global name space when using libraries that come from different vendors.
4. See html manual for full version of this guide.
AUTHORS
Hai Zaar <haizaar@haizaar.com>
Gil Ran <ril@ran4.net>
SEE ALSO ldbash(1), ldbashconfig(8), getopts(1), hashstash(1)colors(1)messages(1)urlcoding(1)locks(1)Linux Epoch Linux
04-18-2017
