udevadm:- udev management tool
ul:- do underlining
umount:- unmount file systems
umount.nfs:- umount.nfs, umount.nfs4 - unmount a Network File System
umount.nfs4:- umount.nfs, umount.nfs4 - unmount a Network File System
uname:- print system information (Ex:- uname)
unexpand:- convert spaces to tabs
unicode_start:- put keyboard and console in unicode mode
unicode_stop:- revert keyboard and console from unicode mode
uniq:- report or omit repeated lines
unix_chkpwd:- Helper binary that verifies the password of the current user
unix_update:- Helper binary that updates the password of a given user
unlink:- call the unlink function to remove the specified file
unshare:- run program with some namespaces unshared from parent
unxz:- xz is a general-purpose data compression tool with command line syntax similar to gzip(1) and bzip2(1). The native file format is the .xz format, but the legacy .lzma format used by LZMA Utils and raw compressed streams with no container format headers are also supported.
unzip:- list, test and extract compressed files in a ZIP archive
unzipsfx:- self-extracting stub for prepending to ZIP archives
update-alternatives:- maintain symbolic links determining default commands
update-ca-trust:- manage consolidated and dynamic configuration of CA certificates and associated trust
updatedb:- update a database for mlocate
update-desktop-database:- Build cache database of MIME types handled by desktop files
update-gtk-immodules:- Update GTK+ immodule cache
update-mime-database:- a program to build the Shared MIME-Info database cache
update-pciids:- download new version of the PCI ID list
uptime:- Tell how long the system has been running. (Ex:- uptime)
usb-devices:- print USB device details (Ex:- usb-devices)
usbhid-dump:- dump USB HID device report descriptors and streams
usb_modeswitch:- switch mode of "multi-state" USB devices
usb_modeswitch_dispatcher:- dispatcher not intended for direct invocation.
useradd:- create a new user or update default new user information
userdel:- delete a user account and related files
userformat:- A graphical tool to mount, unmount and format filesystems.
userhelper:- A helper interface to PAM.
userinfo:- A graphical equivilient to chfn.
usermod:- modify a user account
usermount:- A graphical tool to mount, unmount and format filesystems.
usernetctl:- allow a user to manipulate a network interface if permitted
userpasswd:- A graphical tool to allow users to change their passwords.
users:- print the user names of users currently logged in to the current host
usleep:- sleep some number of microseconds
utmpdump:- dump UTMP and WTMP files in raw formatuuidgen:- create a new UUID value