Ubuntu-L1-Cadet

Basic Os Info

lsb_release -a

Displays Linux distribution details like name, version, and codename. Useful for quickly identifying the Ubuntu release.

$ lsb_release -a

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 25.10
Release:	25.10
Codename:	questing

/etc/os-release

Shows official OS metadata stored in a standard config file. Most reliable source for scripts and system checks.

$ cat /etc/os-release

PRETTY_NAME="Ubuntu 25.10"
NAME="Ubuntu"
VERSION_ID="25.10"
VERSION="25.10 (Questing Quokka)"
VERSION_CODENAME=questing
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=questing
LOGO=ubuntu-logo

hostnamectl

Displays hostname, OS, kernel, architecture, and virtualization info. Used to inspect machine identity and environment.

$ hostnamectl

 Static hostname: lima-default
       Icon name: computer-vm
         Chassis: vm 🖴
      Machine ID: db7a475f8a714aa3badb9968eb8be900
         Boot ID: f0026455776b48bbb2819e991750cbd4
    AF_VSOCK CID: 3
  Virtualization: apple
Operating System: Ubuntu 25.10
          Kernel: Linux 6.17.0-8-generic
    Architecture: arm64
 Hardware Vendor: Apple Inc.
  Hardware Model: Apple Virtualization Generic Platform
Firmware Version: 2069.80.3.0.0
   Firmware Date: Fri 2024-12-13
    Firmware Age: 1y 1month 3w 2d

lscpu

Provides a summarized view of CPU architecture and cores. Best high-level CPU inspection command.

$ lscpu

Architecture:                aarch64
  CPU op-mode(s):            64-bit
  Byte Order:                Little Endian
CPU(s):                      4
  On-line CPU(s) list:       0-3
Vendor ID:                   Apple
  Model name:                -
    Model:                   0
    Thread(s) per core:      1
    Core(s) per cluster:     4
    Socket(s):               -
    Cluster(s):              1
    Stepping:                0x0
    BogoMIPS:                48.00
    Flags:                   fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint bf16 afp sme smei16i64 smef64
                             f64 smei8i32 smef16f32 smeb16f32 smef32f32 sme2 smei16i32 smebi32i32
NUMA:
  NUMA node(s):              1
  NUMA node0 CPU(s):         0-3
Vulnerabilities:
  Gather data sampling:      Not affected
  Ghostwrite:                Not affected
  Indirect target selection: Not affected
  Itlb multihit:             Not affected
  L1tf:                      Not affected
  Mds:                       Not affected
  Meltdown:                  Not affected
  Mmio stale data:           Not affected
  Old microcode:             Not affected
  Reg file data sampling:    Not affected
  Retbleed:                  Not affected
  Spec rstack overflow:      Not affected
  Spec store bypass:         Vulnerable
  Spectre v1:                Mitigation; __user pointer sanitization
  Spectre v2:                Mitigation; CSV2, but not BHB
  Srbds:                     Not affected
  Tsa:                       Not affected
  Tsx async abort:           Not affected
  Vmscape:                   Not affected

cat /proc/cpuinfo

Shows detailed per-core CPU information from the kernel. Useful for low-level debugging and feature detection.

$ cat /proc/cpuinfo

processor	: 0
BogoMIPS	: 48.00
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint bf16 afp sme smei16i64 smef64f64 smei8i32 smef16f32 smeb16f32 smef32f32 sme2 smei16i32 smebi32i32
CPU implementer	: 0x61
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0x000
CPU revision	: 0

processor	: 1
BogoMIPS	: 48.00
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint bf16 afp sme smei16i64 smef64f64 smei8i32 smef16f32 smeb16f32 smef32f32 sme2 smei16i32 smebi32i32
CPU implementer	: 0x61
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0x000
CPU revision	: 0

processor	: 2
BogoMIPS	: 48.00
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint bf16 afp sme smei16i64 smef64f64 smei8i32 smef16f32 smeb16f32 smef32f32 sme2 smei16i32 smebi32i32
CPU implementer	: 0x61
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0x000
CPU revision	: 0

processor	: 3
BogoMIPS	: 48.00
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma lrcpc dcpop sha3 asimddp sha512 asimdfhm dit uscat ilrcpc flagm sb paca pacg dcpodp flagm2 frint bf16 afp sme smei16i64 smef64f64 smei8i32 smef16f32 smeb16f32 smef32f32 sme2 smei16i32 smebi32i32
CPU implementer	: 0x61
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0x000
CPU revision	: 0

uptime

Shows how long the system has been running. Also displays current load averages.

$ uptime

 20:06:19 up 11 days, 12:40,  1 user,  load average: 0.00, 0.00, 0.00

printenv

Lists all environment variables for the current session. Used to debug shell and application behavior.

$ printenv | less

SHELL=/bin/bash
PYENV_SHELL=bash
PWD=/Users/csp/lima_space
LOGNAME=csp
XDG_SESSION_TYPE=tty
HOME=/home/csp.linux

---

File & Directory Navigation

pwd — Show the current working directory

Prints the full path of your current working directory. Useful to confirm where you are in the filesystem.

$ pwd

/Users/csp/kact/lima-base

ls — List files and directories

Lists files and directories in the current location. Options like -l show details, -a shows hidden files.

$ ls

README.md  logfile.txt  one  two

$ ls -1

README.md
logfile.txt
one
two

$ ls -a

.  ..  .ant  .git  .gitignore  README.md  logfile.txt  one  two

cd — Change directory

Changes the current directory. Use .. to go up, ~ to jump to home.

$ cd Documents

$ cd ..

$ cd ~

tree — Display directory structure as a tree (install first)

Displays directories in a hierarchical tree view. Helpful for visualizing project structure.

$ sudo apt install tree

Use 'sudo apt autoremove' to remove them.

Installing:
  tree

$ tree

├── README.md
├── logfile.txt
├── one
│   └── xyz
│       └── file.txt
├── two
│   └── 21
│       └── file.txt
└── ubuntu-20.04.yaml

---

File & Directory Management

touch — Create an empty file

Creates an empty file or updates timestamp. Often used to quickly create placeholder files.

$ touch file.txt

mkdir — Create a directory

Creates a new directory. Supports nested creation with -p.

$ mkdir myfolder

rmdir — Delete an empty directory

Deletes an empty directory only. Fails if the directory contains files.

$ rmdir myfolder

rm — Remove files or directories

Deletes files or directories permanently. -r removes directories recursively—use carefully.

$ rm file.txt
$ rm -r foldername

cp — Copy files or directories

Copies files or directories from source to destination. -r is required for directories.

$ cp file1.txt file2.txt
$ cp -r dir1 dir2

mv — Move or rename files

Moves or renames files and directories. Also used to relocate files across paths.

$ mv old.txt new.txt
$ mv file.txt /tmp/

---

Viewing & Reading Files

cat — Display file contents

Prints the entire file content to terminal. Best for small files.

$ cat file.txt

one
two
error1
error2

less — View file page by page

Views file content page by page. Supports scrolling and search.

$ less file.txt

head — View first lines of a file

Shows the first few lines of a file. Useful for checking file headers.

$ head file.txt

one
two
error1

tail — View last lines of a file

Shows the last few lines of a file. -f follows live updates (logs).

$ tail file.txt

error2
error3

$ tail -f logfile.log

error2
error3

System & User Information

whoami — Show current user

Displays the current logged-in user. Helps verify permissions and identity.

$ whoami

john

uname -a — Show system information

Shows kernel and system architecture info. Useful for debugging OS-level issues.

$ uname

Linux

$ uname -a

Linux lima-default 6.17.0-8-generic #8-Ubuntu SMP PREEMPT_DYNAMIC Fri Nov 14 20:54:15 UTC 2025 aarch64 GNU/Linux

$ uname -r
6.17.0-8-generic

$ uname -m
aarch64

df -h — Show disk usage

Displays disk usage in human-readable format. Helps track storage availability.

$ df -h

Filesystem      Size  Used Avail Use% Mounted on
tmpfs           390M  1.1M  389M   1% /run
efivarfs         56K  1.4K   55K   3% /sys/firmware/efi/efivars
/dev/vda1        96G  5.8G   91G   7% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           2.0G     0  2.0G   0% /tmp
/dev/vda13      891M  113M  716M  14% /boot
/dev/vda15       98M  6.5M   91M   7% /boot/efi
mount0          927G  663G  264G  72% /Users/csp
/dev/vdb        295M  295M     0 100% /mnt/lima-cidata
tmpfs           390M   40K  390M   1% /run/user/501
tmpfs           1.0M     0  1.0M   0% /run/credentials/[e-mail]
tmpfs           1.0M     0  1.0M   0% /run/credentials/[e-mail]
tmpfs           1.0M     0  1.0M   0% /run/credentials/systemd-networkd.service
tmpfs           1.0M     0  1.0M   0% /run/credentials/systemd-journald.service
tmpfs           1.0M     0  1.0M   0% /run/credentials/systemd-resolved.service

free -h — Show memory usage

Shows RAM and swap usage. Essential for monitoring memory pressure.

$ free -h

               total        used        free      shared  buff/cache   available
Mem:           3.8Gi       485Mi       409Mi       1.1Mi       3.1Gi       3.3Gi
Swap:             0B          0B          0B

---

Package Management (Ubuntu-specific)

sudo — Run command as administrator

Runs commands with administrator privileges. Required for system-level changes.

$ sudo apt update

apt update — Update package list

Refreshes package index from repositories. Should be run before installing software.

$ sudo apt update

apt install — Install software

Installs packages from Ubuntu repositories. Automatically resolves dependencies.

$ sudo apt install git

git is already the newest version (1:2.51.0-1ubuntu1).
Summary:
  Upgrading: 0, Installing: 0, Removing: 0, Not Upgrading: 29

apt remove — Remove software

Uninstalls installed packages. Does not remove config files unless specified.

$ sudo apt remove git

Use 'sudo apt autoremove' to remove them.

REMOVING:
  git  ubuntu-server

Summary:
  Upgrading: 0, Installing: 0, Removing: 2, Not Upgrading: 29
  Freed space: 26.3 MB

Continue? [Y/n] y
(Reading database ... 95404 files and directories currently installed.)
Removing ubuntu-server (1.560) ...
Removing git (1:2.51.0-1ubuntu1) ...

---

Searching & Help

find — Search for files

Searches files and directories by name or conditions. Powerful for large directory trees.

$ find . -name file.txt

./one/xyz/file.txt
./two/21/file.txt

grep — Search text inside files

Searches text patterns inside files. Widely used for log analysis.

$ grep "error" logfile.txt

error1
error2
error3

man — View command manual

Displays the official manual for a command. Primary source of truth for CLI tools.

$ man ls

ls(1)                                                                                                          General Commands Manual                                                                                                         ls(1)

NAME
       ls - List directory contents.  Ignore files and directories starting with a '.' by default

SYNOPSIS
       ls  [--help]  [--format] [-C ] [-l|--long] [-x ] [-T|--tabsize] [-m ] [--zero] [-D|--dired] [--hyperlink] [-1 ] [-o ] [-g ] [-n|--numeric-uid-gid] [--quoting-style] [-N|--literal] [-b|--escape] [-Q|--quote-name] [-q|--hide-control-chars]
       [--show-control-chars] [--time] [-c ] [-u ] [--hide] [-I|--ignore]  [-B|--ignore-backups]  [--sort]  [-S  ]  [-t  ]  [-v  ]  [-X  ]  [-U  ]  [-L|--dereference]  [--dereference-command-line-symlink-to-dir]  [-H|--dereference-command-line]
       [-G|--no-group]  [--author]  [-a|--all]  [-A|--almost-all]  [-d|--directory] [-h|--human-readable] [-k|--kibibytes] [--si] [--block-size] [-i|--inode] [-r|--reverse] [-R|--recursive] [-w|--width] [-s|--size] [--color] [--indicator-style]
       [-F|--classify] [--file-type] [-p ] [--time-style] [--full-time] [-Z|--context] [--group-directories-first] [-V|--version] [paths]

DESCRIPTION
       List directory contents.  Ignore files and directories starting with a '.' by default

OPTIONS
       --help Print help information.