I know some articles in this blog are rather clever, but this one is here to remind me (learn from my mistakes!) that understanding how a command thinks is important. I was having some issues with cryptsetup and was told (by Matthew Heon: let me make sure to recognize him for throwing a searchlight at my problem. Thanks!) I the file /usr/share/cracklib/pw_dict.pwd.gz was missing. Fine, this is a CentOS 8 docker container. I can use yum (until they remove it completely) or its replacement, dnf, to look for it. I will be using yum in this discussion knowing that they are interchangeable within the limits of this article.
If the file in in the directory /usr/share/cracklib, chances are it belongs to the cracklib package, so let's begin by seeing what we have matching that:
[root@moe /]# yum search cracklib Failed to set locale, defaulting to C.UTF-8 ========================== Name Exactly Matched: cracklib ========================== cracklib.x86_64 : A password-checking library cracklib.i686 : A password-checking library ========================= Name & Summary Matched: cracklib ========================= cracklib-dicts.x86_64 : The standard CrackLib dictionaries [root@moe /]#
Oh, there are more than one, so we need to be more specific. That is a great job for the whatprovides option; it allows us to find all the packages that contain a given file.
[root@moe /]# yum whatprovides pw_dict.pwd.gz Failed to set locale, defaulting to C.UTF-8 Last metadata expiration check: 0:00:27 ago on Tue Jul 28 20:32:27 2020. Error: No Matches found [root@moe /]#I did learn that sometimes looking for a package by just providing the filename of a file that belongs to it does not work well, but if you make it look like you are giving a path will work. And this path can begin with a * so it can expand the path to any path in the system. So, let's try that and hope for the best:
[root@moe /]# yum whatprovides */pw_dict.pwd.gz Failed to set locale, defaulting to C.UTF-8 Last metadata expiration check: 17:43:12 ago on Tue Jul 28 20:32:27 2020. Error: No Matches found [root@moe /]#What is going on? Well, let's up on a limb: of the three cracklib-related files, cracklib-dicts seems to be the one with the most potential because the file we want is a dictionary. And then see what lurks in /usr/share/cracklib/:
[root@moe /]# yum install cracklib-dicts [...] [root@moe /]# ls /usr/share/cracklib/ cracklib-small.hwm cracklib-small.pwi pw_dict.hwm pw_dict.pwi cracklib-small.pwd cracklib.magic pw_dict.pwd [root@moe /]#
A candle lights over my heard, indicating I was enlightened: it is called pw_dict.pwd, not pw_dict.pwd.gz! I did not account for it to be in a different format (gzipped in this case)! Well duh!
With that in mind, we should see if we could have saved some aggravation. We expanded the search path by entering */pw_dict.pwd.gz before; would that work for the filename? Let's find out:
[root@moe /]# yum whatprovides */pw_dict.pwd Failed to set locale, defaulting to C.UTF-8 Last metadata expiration check: 17:43:45 ago on Tue Jul 28 20:32:27 2020. cracklib-dicts-2.9.6-15.el8.x86_64 : The standard CrackLib dictionaries Repo : @System Matched from: Filename : /usr/share/cracklib/pw_dict.pwd cracklib-dicts-2.9.6-15.el8.x86_64 : The standard CrackLib dictionaries Repo : BaseOS Matched from: Filename : /usr/share/cracklib/pw_dict.pwd [root@moe /]# yum whatprovides pw_dict.* Failed to set locale, defaulting to C.UTF-8 Last metadata expiration check: 17:46:32 ago on Tue Jul 28 20:32:27 2020. Error: No Matches found [root@moe /]# [root@moe /]# yum whatprovides */pw_dict.* Failed to set locale, defaulting to C.UTF-8 Last metadata expiration check: 17:44:42 ago on Tue Jul 28 20:32:27 2020. cracklib-dicts-2.9.6-15.el8.x86_64 : The standard CrackLib dictionaries Repo : @System Matched from: Filename : /usr/share/cracklib/pw_dict.hwm Filename : /usr/share/cracklib/pw_dict.pwd Filename : /usr/share/cracklib/pw_dict.pwi cracklib-dicts-2.9.6-15.el8.x86_64 : The standard CrackLib dictionaries Repo : BaseOS Matched from: Filename : /usr/share/cracklib/pw_dict.hwm Filename : /usr/share/cracklib/pw_dict.pwd Filename : /usr/share/cracklib/pw_dict.pwi [root@moe /]# yum whatprovides */*_dict.pwd Failed to set locale, defaulting to C.UTF-8 cracklib-dicts-2.9.6-15.el8.x86_64 : The standard CrackLib dictionaries Repo : BaseOS Matched from: Filename : /usr/lib64/cracklib_dict.pwd Filename : /usr/share/cracklib/pw_dict.pwd [root@moe /]#
Interesting that we really do not need to tack a * to the end of the search pattern. So, what we learned from this article is that if searching for a package a given file belongs to does not work, we can broaden the search by replacing part of the filename in question with a *. And that we do not need that if the bit of the filename we are taking is at the end.
Learning something useful in this blog: who would've thought?
