Red Hat Summit Red Hat SummitSupportConsoleDevelopersStart a trialContact

Chapter 21. Shells and command-line tools

The following chapters contain the most notable changes to shells and command-line tools between RHEL 9 and RHEL 10.

21.1. Notable changes to system management
Copy link

The perl(Mail::Sender) module has been removed
The perl(Mail::Sender) module is removed from RHEL 10 without any replacement. As a consequence, the checkbandwidth script from net-snmp-perl package does not support email alerts when bandwidth high/low levels for a host or interface are reached.

21.2. Notable changes to command line tools
Copy link

cgroupsv1 is a removed functionality in RHEL 10
cgroups is a kernel subsystem used for process tracking, system resource allocation, and partitioning. In previous versions, systemd service manager supported booting in the cgroups v1 and in cgroups v2 mode (with v1 as the default in rhel8 and v2 as the default in rhel9). In Red Hat Enterprise Linux 10, systemd will nolonger support booting in the cgroups v1 mode; only cgroups v2 mode will be available.
RHEL 10 provides ReaR in version 2.9

The ReaR utility has been upgraded to version 2.9. The notable changes include:

  • On IBM Z, the IPL output method is now deprecated. The RAMDISK output method is provided as an alternative. The OUTPUT=RAMDISK functionality is identical on all the supported hardware architectures, unlike the deprecated OUTPUT=IPL functionality, which is specific to IBM System Z.

    Note that the names of the recovery ramdisk image and the kernel that are generated by ReaR are different with OUTPUT=RAMDISK. The kernel is named kernel-$RAMDISK_SUFFIX and the ramdisk image is named initramfs-$RAMDISK_SUFFIX.img. The RAMDISK_SUFFIX is a configuration variable that you can set in /etc/rear/local.conf. If the variable is not set, it defaults to the host name of the system. If you used the OUTPUT=IPL setting with previous ReaR versions, change it to OUTPUT=RAMDISK and adjust any automation that uses the resulting kernel and ramdisk image files according to the new naming convention described above to be compatible with future ReaR versions when the IPL output method is removed.

  • The default value of the ISO_VOLID configuration variable, which specifies the label of the resulting ISO image when using the OUTPUT=ISO setting, was changed to REAR-ISO. The default in previous ReaR versions was RELAXRECOVER. If you need to mount the resulting ISO 9660 file system by label, adjust the mount command for the label change. Alternatively, you can set the ISO_VOLID variable in /etc/rear/local.conf to RELAXRECOVER to restore the former behavior.
Back to top
Red Hat logoGithubredditYoutubeTwitter

Learn

Try, buy, & sell

Communities

About Red Hat Documentation

We help Red Hat users innovate and achieve their goals with our products and services with content they can trust. Explore our recent updates.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. For more details, see the Red Hat Blog.

About Red Hat

We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.

Theme

© 2026 Red Hat