Bootstrap

$? (exit code or return code)

Add a label to a partition using the e2label command

Add swap space to a Linux partition

alias (create commands)

apt-cache (search for a package)

apt-get (install update packages)

arp (address resolution protocol)

at (schedule a one time job)

batch (schedule jobs)

blkid command (determine file system type)

bunzip2 (unzip a bzip2 archive)

bzip2 (compress file)

Capture packets using the tcpdump command

cat or tac (view the content of a file)

chage (user account aging information expire password)

Check a file system for errors in Linux

chkconfig (runlevel)

chmod (change a file or directory standard permissions)

chown (change ownership)

Common vi editor commands

cpio (create, view, and extract an archive)

Create a disk partition using the fdisk command

Create file using the touch command

Create hard, soft and symbolic links (symlink) using the ln command

debugfs command (recover a deleted file)

Delete a disk partition using the fdisk command

Delete files and directories using the rm (remove) command

df command (disk filesystem usage)

dhclient (dhcp - obtain, renew, and release IP address)

diff command (differences between files)

dig (name server lookup DNS)

dig (view DNS information)

Display CPU details using the lscpu command

Display file atime ctime mtime using the stat command

Display how long server has been running using the uptime command

Display IP address info using the ip command

Display when system was last rebooted using the who command

edquota (edit quota)

exec (execute a command)

expand (replace tabs with spaces)

file command (determine file system type)

file command (determine file type)

Filter output using awk

Filter output using grep

find command - date accessed (-atime)

find command - date changed (-ctime)

find command - date modified (-mtime)

find command - exclude "permission denied"

find command - exclude directories from search (-not -path)

find command - Exclude file systems from search (-xdev)

find command - executable files

find command - hidden files and directories

find command - mindepth and maxdepth

find files owned by group

find files owned by user

Find files that are greater than or less than a certain size

find files that match permission

Find files using the locate command

free (view RAM memory)

fuser (determine the PID of a file)

fuser (view kill processes)

gdisk (format disk partition)

genkey (create a public / private key pair using crypto-utils)

getfacl (view access control entries)

gpasswd (change group password)

grep (--exclude-dir)

groupadd (create group)

groupmod (modify group)

growisofs (burn CD or DVD)

gunzip (unzip a gzip archive)

gzip (compress file)

How to use the DD and mkisofs commands to create an ISO or IMG file in Linux

htpasswd (delete user)

hwclock (hardware clock)

iconv (character encoding standard)

ifconfig (IP address information)

ifconfig command (temporarily change the MAC address)

ifconfig promisc (promiscuous mode)

Increase the size of a disk partition using the fdisk command

info (information about a command)

insmod (insert a module)

ip neighborhood (view address resolution cache)

ipcrc (remove semaphores)

ipcs (list semaphores)

isql (connect to a database)

isql --version (SQL version)

join (combine or merge lines in two different files)

journalctl (view the journal)

journalctl (word wrap text)

journalctl --since and --until filters

kill (end a process)

killall (end a process)

last (view current and recently logged in users)

Linux LANG variable with examples

List CPU stats using the sar command

List environment variables using the env command

List environment variables using the printenv command

List files and directories using the find command

List files and directories using the ls command

List LDAP and local user accounts using the getent passwd command

List partitions using the fdisk command

List shared libraries modules using the ldd command

List the amount of memory and CPU used using the top command

List the amount of space being using the du (disk usage) command

locale (language, country, character encoding standard)

logger (add records to a log file)

lprm (remove print jobs)

lpstat (list available printers)

lsblk command (list hard drive solid state drive)

lsmod (list loaded modules)

man (view manual for a command)

mdadm --detail (show details of RAID array)

mdadm --examine (partition RAID)

mdadm --stop (stop a RAID array)

mkdir (make directory)

mke2fs (create a file system)

mkfs (create a file system)

Modify Network Manager using the nmlci command

modinfo (view module information)

modprobe (insert and remove modules)

Mount a partition or share using the mount command

netstat (view network connections)

nice (influence a process to run with higher or lower priority)

nohup command (run a process while logged out)

nslookup (name server lookup DNS)

ntpdate (synchronize to an NTP server)

ntpq (view NTP servers being used)

parted (format disk partition)

passwd (change a users password)

paste (read, delimit, combine files)

pdbedit command (Samba users)

pr (format file for printing)

printf (print output)

Prompt for user input using the read command

ps commad - show processes being run by a certain user (-U)

ps command (process PID)

ps command - add additional columns (-f)

ps command - display a process associated with a certain PID (-p)

ps command - display how long a process has been running (-o etime etimes)

ps command - show all running processes (-e -A ax)

ps command - show processes being run by a system service (-C)

quotacheck command (check disk quota)

quotaon (enable quota)

regex using awk and gsub

Remove a module using the rmmod command

Remove directory using rmdir

renice (influence a process to run with higher or lower priority)

repquota command (view quota)

resolvectl command (DNS)

route (view and create network routes)

rpm2cpio command (compress an RPM package into a CPIO archive)

schedule reoccurring jobs using crontab (cron table)

scp (transfer files using secure copy protocol)

sed (replace string)

Send and retrieve email using the mail command

Send and retrieve email using the sendmail command

seq (sequence of numbers)

Set file atime ctime mtime using the touch command

setfacl (create update access control entries)

Setting Alternatives

Setting time zone using the TZ variable

shutdown (shutdown, reboot, halt, poweroff)

source (export variable)

split (divide a single file into multiple files)

ssh-keyscan command (get SSH keys)

star (create, view, extract an archive)

sudo (give a group permission to run certain commands)

sudo (give a user permission to run certain commands)

tee (redirect output to both the console and a file)

tr (trade, replace, change characters)

tracepath (trace route to a host)

tzselect (time zone select)

ulimit (list and update a users limits)

umask (view and update default permission masks)

umount (unmount a partition or share)

uname (display information about the kernel)

unexpand (replace spaces with tabs in a file)

unfold (unwrap text)

uniq (filter unique lines)

unset (undefine a variable)

useradd (create a user account)

userdel (delete user account)

usermod (modifying a users account)

Using DPKG to manage Debian packages in Linux

Validate an XML and XSD file using the xmllint command

View logged in users using the who command

Viewing boot events using dmesg or the boot.log

w (view logged in users)

wall (send message to other systems)

watch command (run a command once every x seconds)

wc (count words, characters, and lines)

wget (download files from remote systems)

xargs (convert stdin to an argument)

xml_grep (parse XML file)

xwininfo command (display information about a window)

yum (download, install, remove, update packages)

yumdownloader (download a package)

How to access an SD Card on a Samsung device using Linux

Return directory name using dirname

Understanding the X font server in Linux

Resolve "Sorry, user is not allowed to execute as root"

Resolve "End of central directory signature not found"

Resolve "failure: repodata/repomd.xml from rhel-7-server-optional-rpms: [Errno 256] No more mirrors to try."

Resolve "Mount Error(5) Input/Output error"

Resolve "mount: bad option; for several filesystems (e.g. nfs, cifs) you might need a /sbin/mount.<type> helper program."

Resolve "not allowed to run sudo"

Resolve "Read Only File System"

Resolve "The semaphore timeout period has expired"

Resolve "too many open files"

Resolve "ulimit: open files: cannot modify limit: Operation not permitted"

Resolve error "Mount Error(13) Permission Denied"

Linux Commands articles