Requirements
One will always need a connected computer with same OS and Version in order to ascertain the dependent packages that need to be downloaded for the disconnected (air-gapped) computer.
Centos 7 Example
On Redhat and Centos OS, tar and libnsl may need to be pre-installed as they are needed to unpack the installer runfile:
# Navigate to a clean directory to download packages to
mkdir -p /tmp/omk_opXyz_packages
cd /tmp/omk_opXyz_packages# Extract the list of dependent packages:
yum -q deplist tar;
package: tar.x86_64 2:1.26-35.el7dependency: /bin/sh
provider: bash.x86_64 4.2.46-34.el7
dependency: /sbin/install-info
provider: info.x86_64 5.1-5.el7
dependency: libacl.so.1()(64bit)
provider: libacl.x86_64 2.2.51-15.el7
dependency: libacl.so.1(ACL_1.0)(64bit)
provider: libacl.x86_64 2.2.51-15.el7
dependency: libc.so.6(GLIBC_2.17)(64bit)
provider: glibc.x86_64 2.17-307.el7.1
dependency: libselinux.so.1()(64bit)
provider: libselinux.x86_64 2.5-15.el7
dependency: rtld(GNU_HASH)
provider: glibc.x86_64 2.17-307.el7.1
provider: glibc.i686 2.17-307.el7.1# libnsl is not needed in this example as no package is returned:
yum -q deplist libnsl# Download each of the dependent packages:
# yumdownloader <package1> <package2>…
yumdownloader tar.x86_64Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
epel/x86_64/metalink | 2.8 kB 00:00:00
* base: mirror.ventraip.net.au
* epel: mirror.aarnet.edu.au
* extras: mirror.ventraip.net.au
* updates: mirror.ventraip.net.au
base | 3.6 kB 00:00:00
epel | 4.7 kB 00:00:00
extras | 2.9 kB 00:00:00
updates
tar-1.26-35.el7.x86_64.rpm# Downloaded packages will now be in the current directory:
ls -la-rw-r--r--. 1 root root 865848 Nov 12 2018 tar-1.26-35.el7.x86_64.rpm