Practice 001 — General Shell Commands
Terminal Session
# General Syntax of Commands
# command_name [options] <arguments>
[aadarsha@labserver ~]$ touch file1 file2 file3
[aadarsha@labserver ~]$ ls
file1 file2 file3
[aadarsha@labserver ~]$ pwd
/home/aadarsha
[aadarsha@labserver ~]$ ls /
afs boot etc lib media opt root sbin sys usr
bin dev home lib64 mnt proc run srv tmp var
[aadarsha@labserver ~]$ ls /etc/
adjtime firewalld magic samba
aliases fonts makedumpfile.conf.sample sasl2
alternatives fstab man_db.conf security
anacrontab GREP_COLORS microcode_ctl selinux
audit groff mke2fs.conf services
authselect group modprobe.d sestatus.conf
bash_completion.d group- modules-load.d shadow
bashrc grub2.cfg motd shadow-
bindresvport.blacklist grub.d motd.d shells
binfmt.d gshadow mtab skel
centos-release gshadow- netconfig ssh
chrony.conf gss NetworkManager ssl
cifs-utils host.conf networks sssd
credstore hostname nftables statetab.d
credstore.encrypted hosts nsswitch.conf subgid
cron.d inittab nvme subgid-
cron.daily inputrc openldap subuid
cron.deny iproute2 opt subuid-
cron.hourly issue os-release sudo.conf
cron.monthly issue.d pam.d sudoers
crontab issue.net passwd sudoers.d
cron.weekly kdump passwd- sudo-ldap.conf
crypto-policies kdump.conf pkcs11 sysconfig
crypttab kernel pki sysctl.conf
csh.cshrc keys pm sysctl.d
csh.login keyutils popt.d systemd
dbus-1 krb5.conf printcap system-release
dconf krb5.conf.d profile system-release-cpe
debuginfod ld.so.cache profile.d terminfo
default ld.so.conf protocols tmpfiles.d
depmod.d ld.so.conf.d rc.d tpm2-tss
dhcp libaudit.conf rc.local udev
DIR_COLORS libnl redhat-release vconsole.conf
DIR_COLORS.lightbgcolor libssh request-key.conf virc
dnf locale.conf request-key.d X11
dracut.conf localtime resolv.conf xattr.conf
dracut.conf.d login.defs rpc xdg
environment logrotate.conf rpm yum
ethertypes logrotate.d rsyslog.conf yum.conf
exports lvm rsyslog.d yum.repos.d
filesystems machine-id rwtab.d
[aadarsha@labserver ~]$ ls -l /etc
total 1044
-rw-r--r--. 1 root root 16 May 26 15:36 adjtime
-rw-r--r--. 1 root root 1529 Nov 29 2023 aliases
drwxr-xr-x. 2 root root 4096 May 26 15:34 alternatives
-rw-r--r--. 1 root root 541 Jan 14 05:45 anacrontab
drwxr-x---. 4 root root 100 May 26 15:33 audit
drwxr-xr-x. 3 root root 4096 May 26 15:34 authselect
drwxr-xr-x. 2 root root 38 May 26 15:34 bash_completion.d
-rw-r--r--. 1 root root 2709 Nov 29 2023 bashrc
...
...
lrwxrwxrwx. 1 root root 12 Mar 25 05:45 yum.conf -> dnf/dnf.conf
drwxr-xr-x. 2 root root 51 Apr 7 05:45 yum.repos.d
[aadarsha@labserver ~]$ ls -l
total 0
-rw-r--r--. 1 aadarsha aadarsha 0 Jun 4 21:29 file1
-rw-r--r--. 1 aadarsha aadarsha 0 Jun 4 21:29 file2
-rw-r--r--. 1 aadarsha aadarsha 0 Jun 4 21:29 file3
[aadarsha@labserver ~]$
[aadarsha@labserver ~]$ whoami
aadarsha
[aadarsha@labserver ~]$
[aadarsha@labserver ~]$ date
Thu Jun 4 09:33:38 PM +0545 2026
[aadarsha@labserver ~]$ cal
June 2026
Su Mo Tu We Th Fr Sa
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
[aadarsha@labserver ~]$ ls
file1 file2 file3
[aadarsha@labserver ~]$ mkdir dir1 dir2 dir3
[aadarsha@labserver ~]$ ls
dir1 dir2 dir3 file1 file2 file3
# running multiple commands at a time
[aadarsha@labserver ~]$ date; cal; ls
Thu Jun 4 09:34:10 PM +0545 2026
June 2026
Su Mo Tu We Th Fr Sa
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
dir1 dir2 dir3 file1 file2 file3
[aadarsha@labserver ~]$ date && cal && ls
Thu Jun 4 09:34:31 PM +0545 2026
June 2026
Su Mo Tu We Th Fr Sa
1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
dir1 dir2 dir3 file1 file2 file3
Note:
# in case of ; --> each command runs independently
# in case of && --> if previous command doesn't run successfully then the following command doesn't run
[aadarsha@labserver ~]$ date && call && ls && whoami
Thu Jun 4 09:36:56 PM +0545 2026
-bash: call: command not found
# check success or failure status of the last run command or script
[aadarsha@labserver ~]$ echo $?
0
# if o/p of "echo $?" --> 0, the command or script run successfully
# if o/p of "echo $?" --> other than 0, the command or script don't run successfully
[aadarsha@labserver ~]$ who
aadarsha tty1 2026-06-04 21:25
aadarsha pts/0 2026-06-04 21:26 (192.168.254.152)
[aadarsha@labserver ~]$ wrongcommand
-bash: wrongcommand: command not found
[aadarsha@labserver ~]$ echo $?
127
[aadarsha@labserver ~]$