Yum

Useful commands:

repoquery -i itcl - tells which repository contains itcl package

To remove package:

yum --setopt=tsflags=noscripts remove <package>

Sometimes it is useful to delete some files:

rm -f /var/lib/rpm/__db.*

On CensOS on VTP, it was some problem:

Hi Bryan,
on yum updates, I tried
  [base]
  name=CentOS-$releasever - Base
  baseurl=http://vault.centos.org/altarch/$releasever/os/$basearch/
and it gives me this:
  http://vault.centos.org/altarch/7/os/armhfp/repodata/repomd.xml: [Errno 14] HTTPS Error 301 - Moved Permanently
  Trying other mirror.
If I change 'http:' to 'https:' it gives me this:
  https://vault.centos.org/altarch/7/os/armhfp/repodata/repomd.xml: [Errno 14] curl#60 - "Peer's certificate issuer has been marked as not trusted by the user."
  Trying other mirror.
I added key
 sslverify=0
on the next line after https:... and yum seems updating now, will see.
Sergey

Final /etc/yum.repos.d/CentOS-Base.repo looks like this ($releasever=7 and $basearch=armhfp):

[base]
name=CentOS-$releasever - Base
baseurl=https://vault.centos.org/altarch/$releasever/os/$basearch/
sslverify=0
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
       file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32

#released updates 
[updates]
name=CentOS-$releasever - Updates
baseurl=https://vault.centos.org/altarch/$releasever/updates/$basearch/
sslverify=0
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
       file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=https://vault.centos.org/altarch/$releasever/extras/$basearch/
sslverify=0
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
       file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://vault.centos.org/altarch/$releasever/centosplus/$basearch/
sslverify=0
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
       file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-SIG-AltArch-Arm32