Terminal Session
Lab Environment
- OS: CentOS Stream 10
- Architecture: x86_64
- Virtualization: VirtualBox
- CPU: 2 vCPU
- Memory: ~1.7 GiB
- Filesystem: XFS
- Storage: LVM
System Identity
# Displays the system's network hostname.
[aadarsha@labserver ~]$ hostname
labserver
# Shows current username
[aadarsha@labserver ~]$ whoami
aadarsha
# Show comprehensive system information including OS version, kernel, and virtualization details.
[root@labserver ~]# hostnamectl
Static hostname: labserver
Icon name: computer-vm
Chassis: vm 🖴
Machine ID: <redacted>
Boot ID: <redacted>
Product UUID: <redacted>
Virtualization: oracle
Operating System: CentOS Stream 10 (Coughlan)
CPE OS Name: cpe:/o:centos:centos:10
Kernel: Linux 6.12.0-228.el10.x86_64
Architecture: x86-64
Hardware Vendor: innotek GmbH
Hardware Model: VirtualBox
Hardware Serial: <redacted>
Firmware Version: VirtualBox
Firmware Date: Fri 2006-12-01
Firmware Age: 19y 7month 2w 2d
# Shows user ID, group ID, and group memberships
[aadarsha@labserver ~]$ id
uid=1000(aadarsha) gid=1000(aadarsha) groups=1000(aadarsha),10(wheel) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
# Show current directory
[aadarsha@labserver ~]$ pwd
/home/aadarsha
Operating System and Kernel
# Displays the running kernel release.
[aadarsha@labserver ~]$ uname -r
6.12.0-228.el10.x86_64
# Displays multiple kernel/system attributes, including kernel name, hostname, kernel release, kernel version, machine architecture, and operating-system information.
[aadarsha@labserver ~]$ uname -a
Linux labserver 6.12.0-228.el10.x86_64 #1 SMP PREEMPT_DYNAMIC Thu May 14 14:51:31 UTC 2026 x86_64 GNU/Linux
# Show Linux distribution details
[aadarsha@labserver ~]$ cat /etc/os-release
NAME="CentOS Stream"
VERSION="10 (Coughlan)"
RELEASE_TYPE=stable
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="10"
PLATFORM_ID="platform:el10"
PRETTY_NAME="CentOS Stream 10 (Coughlan)"
ANSI_COLOR="0;31"
LOGO="fedora-logo-icon"
CPE_NAME="cpe:/o:centos:centos:10"
HOME_URL="https://centos.org/"
VENDOR_NAME="CentOS"
VENDOR_URL="https://centos.org/"
BUG_REPORT_URL="https://issues.redhat.com/"
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux 10"
REDHAT_SUPPORT_PRODUCT_VERSION="CentOS Stream"
[aadarsha@labserver ~]$
CPU and Memory
# Detailed memory statistics from the kernel
[aadarsha@labserver ~]$ head /proc/meminfo
MemTotal: 1745836 kB
MemFree: 1304920 kB
MemAvailable: 1380824 kB
Buffers: 5304 kB
Cached: 198944 kB
SwapCached: 0 kB
Active: 190272 kB
Inactive: 94280 kB
Active(anon): 85168 kB
Inactive(anon): 0 kB
# Number of processing units
[aadarsha@labserver ~]$ nproc
2
# Memory Information
[aadarsha@labserver ~]$ free -h
total used free shared buff/cache available
Mem: 1.7Gi 363Mi 1.1Gi 4.8Mi 308Mi 1.3Gi
Swap: 2.0Gi 0B 2.0Gi
| Field | Meaning |
|---|
| total | Total installed RAM |
| used | Memory currently used |
| free | Memory currently unused and not allocated to anything. |
| shared | Shared memory |
| buff/cache | Memory used by kernel cache |
| available | Memory available for new processes |
| Swap | Swap partition usage |
For practical memory availability, available is generally more useful than free.
Storage and Filesystems
# Shows the block-device/storage topology: (disks and partitions) in a tree format
# LVM (Logical Volume Manager) is being used for flexible storage management
[aadarsha@labserver ~]$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 0 25.1G 0 disk
├─sda1 8:1 0 2M 0 part
├─sda2 8:2 0 1G 0 part /boot
└─sda3 8:3 0 24G 0 part
├─cs-root 253:0 0 17G 0 lvm /
├─cs-swap 253:1 0 2G 0 lvm [SWAP]
└─cs-var 253:2 0 5G 0 lvm /var
sr0 11:0 1 1024M 0 rom
# Shows mounted filesystems
[aadarsha@labserver ~]$ mount | head
/dev/mapper/cs-root on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=849912k,nr_inodes=212478,mode=755,inode64)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel,inode64,usrquota)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,seclabel,nsdelegate,memory_recursiveprot)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime,seclabel)
bpf on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
# Disk Information
# Shows filesystem capacity and usage for mounted filesystems.
[aadarsha@labserver ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/cs-root 16G 1.6G 15G 10% /
devtmpfs 830M 0 830M 0% /dev
tmpfs 853M 0 853M 0% /dev/shm
tmpfs 341M 4.9M 337M 2% /run
tmpfs 1.0M 0 1.0M 0% /run/credentials/systemd-journald.service
/dev/sda2 2.0G 405M 1.6G 21% /boot
tmpfs 1.0M 0 1.0M 0% /run/credentials/getty@tty1.service
tmpfs 171M 4.0K 171M 1% /run/user/1000
| Field | Meaning |
|---|
| Filesystem | Mounted filesystem |
| Size | Total filesystem size |
| Used | Used space |
| Avail | Available space |
| Use% | Percentage used |
| Mounted on | Mount point |
[aadarsha@labserver ~]$ ls
dir1 dira impfiles.tar newimpfiles.tar.gz testcompany testfile words words.gz
# stat reports filesystem metadata; it is not merely another way to display the contents or type of a file.
# timestamp
- Access — last access time
- Modify — file content modification time
- Change — inode metadata/status change time
- Birth — creation time, when supported by the filesystem/platform
[aadarsha@labserver ~]$ stat testfile
File: testfile
Size: 56 Blocks: 8 IO Block: 4096 regular file
Device: 253,0 Inode: 526546 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/aadarsha) Gid: ( 1000/aadarsha)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2026-06-07 21:33:39.784384746 +0545
Modify: 2026-06-07 21:33:34.476381274 +0545
Change: 2026-06-07 21:33:34.476381274 +0545
Birth: 2026-06-07 09:23:07.596008113 +0545
[aadarsha@labserver ~]$ stat impfiles.tar
File: impfiles.tar
Size: 11704320 Blocks: 22864 IO Block: 4096 regular file
Device: 253,0 Inode: 527801 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2026-06-08 16:35:14.826687643 +0545
Modify: 2026-06-08 16:38:29.505323470 +0545
Change: 2026-06-08 16:38:29.505323470 +0545
Birth: 2026-06-08 16:34:03.703711086 +0545
[aadarsha@labserver ~]$ ls -lh dir1/
total 0
drwxr-xr-x. 3 aadarsha aadarsha 18 Jun 7 15:41 dir2
-rw-r--r--. 1 aadarsha aadarsha 0 Jun 7 15:48 numfile
[aadarsha@labserver ~]$ ls -lh dira
total 4.8M
drwxr-xr-x. 3 aadarsha aadarsha 18 Jun 8 07:50 dirb
-rw-r--r--. 1 aadarsha aadarsha 0 Jun 7 16:10 letfile
-rw-r--r--. 1 aadarsha aadarsha 73 Jun 8 08:47 myfile_hard
-rw-r--r--. 1 aadarsha aadarsha 4.8M Jun 8 09:52 words
[aadarsha@labserver ~]$ ls -ld dira # to see the details of the directory itself
drwxr-xr-x. 3 aadarsha aadarsha 65 Jun 8 12:07 dira
[aadarsha@labserver ~]$ stat dira
File: dira
Size: 65 Blocks: 0 IO Block: 4096 directory
Device: 253,0 Inode: 25447633 Links: 3
Access: (0755/drwxr-xr-x) Uid: ( 1000/aadarsha) Gid: ( 1000/aadarsha)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2026-06-08 12:07:35.289248194 +0545
Modify: 2026-06-08 12:07:19.877766384 +0545
Change: 2026-06-08 12:07:19.877766384 +0545
Birth: 2026-06-07 15:42:17.367604410 +0545
[aadarsha@labserver ~]$ ls
dir1 dira impfiles.tar newimpfiles.tar.gz testcompany testfile words words.gz
[aadarsha@labserver ~]$ file testfile
testfile: ASCII text
[aadarsha@labserver ~]$ file words.gz
words.gz: gzip compressed data, was "words", last modified: Mon Jun 8 04:07:53 2026, from Unix, original size modulo 2^32 4953598
[aadarsha@labserver ~]$ file newimpfiles.tar.gz
newimpfiles.tar.gz: gzip compressed data, from Unix, original size modulo 2^32 6737920
# note:
# /etc/skel contains files and directories that are used as templates when creating a new user's home directory. The exact contents depend on the distribution and system configuration.
# cp /etc/skel/.bashrc . ( copy .bashrc here )
-------------------------------------------------------------------------------------------------
[aadarsha@labserver ~]$ ls
dir1 dira extracted impfiles.tar newimpfiles.tar.gz testcompany testfile words words.gz
# Getting Help
[aadarsha@labserver ~]$ ls -l --color=auto
total 18488
drwxr-xr-x. 3 aadarsha aadarsha 33 Jun 8 06:47 dir1
drwxr-xr-x. 3 aadarsha aadarsha 65 Jun 8 12:07 dira
drwxr-xr-x. 4 root root 28 Jun 8 20:16 extracted
-rw-r--r--. 1 root root 11704320 Jun 8 16:38 impfiles.tar
-rw-r--r--. 1 root root 784897 Jun 8 16:33 newimpfiles.tar.gz
drwxr-xr-x. 5 aadarsha aadarsha 54 Jun 7 07:24 testcompany
-rw-r--r--. 1 aadarsha aadarsha 56 Jun 7 21:33 testfile
-rw-r--r--. 1 aadarsha aadarsha 4953598 Jun 8 09:52 words
-rw-r--r--. 1 aadarsha aadarsha 1476067 Jun 8 12:09 words.gz
# using man command
[aadarsha@labserver ~]$ man ls
# search text in man page
# /text
/text Search forward
n Next match
N Previous match
Space Next page
b Previous page
q Quit
# use n: next forward direction and N: backward direction
[aadarsha@labserver ~]$ man ls
[aadarsha@labserver ~]$ ls -Sl /etc
total 1048
-rw-r--r--. 1 root root 701707 Nov 29 2023 services
...
...
-rw-r--r--. 1 root root 0 Nov 29 2023 subuid-
[aadarsha@labserver ~]$ man ls
[aadarsha@labserver ~]$ ls -Slr /etc
total 1048
-rw-r--r--. 1 root root 0 Nov 29 2023 subuid-
...
...
-rw-r--r--. 1 root root 6714 Nov 29 2023 protocols
-rw-r--r--. 1 root root 8782 May 26 15:33 kdump.conf
-rw-r--r--. 1 root root 8888 Feb 23 05:45 login.defs
-rw-r--r--. 1 root root 13567 Jun 8 16:27 ld.so.cache
-rw-r--r--. 1 root root 701707 Nov 29 2023 services
[aadarsha@labserver ~]$ ls -S -l -r /etc
total 1048
-rw-r--r--. 1 root root 0 Nov 29 2023 subuid-
-rw-r--r--. 1 root root 0 Nov 29 2023 subgid-
-rw-r--r--. 1 root root 0 Nov 29 2023 motd
...
...
-rw-r--r--. 1 root root 701707 Nov 29 2023 services
# man -k <key word related to task>
# Searches the manual-page database by keyword/description.
[aadarsha@labserver ~]$ man -k copy # use: apropos copy
cp (1) - copy files and directories
cpio (1) - copy files to and from archives
dd (1) - convert and copy a file
install (1) - copy files and set attributes
scp (1) - OpenSSH secure file copy
sg_copy_results (8) - send SCSI RECEIVE COPY RESULTS command (XCOPY related)
sg_dd (8) - copy data to and from files and devices, especially SCSI devices
sg_xcopy (8) - copy data to and from files and devices using SCSI EXTENDED COPY (XCOPY)
sgm_dd (8) - copy data to and from files and devices, especially SCSI devices
sgp_dd (8) - copy data to and from files and devices, especially SCSI devices
ssh-copy-id (1) - use locally available keys to authorise logins on a remote machine
xfs_copy (8) - copy the contents of an XFS filesystem
xfs_metadump (8) - copy XFS filesystem metadata to a file
xfs_rtcp (8) - XFS realtime copy command
[aadarsha@labserver ~]$ man -k "copy file"
cp (1) - copy files and directories
cpio (1) - copy files to and from archives
install (1) - copy files and set attributes
aadarkdk@pop-os:~$ ls -lS /etc/
...
-l --> long listing format
-S --> sort by file size, largest first (descending)
aadarkdk@pop-os:~$ ls -Slr /etc # ls -lS --reverse /etc
...
- -r --> reverse
getting online help:
- Primary references: vendor documentation, local man pages and official docs,eg: docs.redhat.com
- Secondary references: tutorials, blogs, community discussions