[Linux] Linux Commands Cheat Sheet (Linux 명령어 정리)

LINUX (RHEL/CENTOS) 명령어 정리

목차

• 시스템 명령어
  • 시스템 명령어
  • 프로세스 관리
  • 스케줄
  • 시스템 ETC
• 파일 및 디렉토리 명령어
  • 파일 명령어
  • 디렉터리 명령어
  • 파일 내용 접근 명령어
  • 검색
• 유저 관리(Administration)
  • 유저
  • 그룹
  • 파일 권한
  • 유저 ETC
• 네트워크
  • 네트워크
  • 네트워크 연결 확인
  • DNS
  • 연결
  • HTTP
• 하드웨어
  • 하드웨어
  • 모듈
• 디스크 유틸(Utilities)
  • HDD
  • 파티션
  • Swap
  • 파일 시스템
  • 데이터
  • 마운트
• 성능
  • 성능

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시스템 명령어

시스템 명령어

명령어	설명	예시
shutdown	bring the system down	shutdown -h now ← -h = Halt or poweroff after shutdown
shutdown -r now ← -r = Reboot after shutdown
shutdown -r -F now ← -F = Force fsck after reboot.
halt	stop the system	halt
reboot	reboot the system.	reboot
init		init 1 #change to single usermode
uptime	Tell how long the system has been running.	uptime
runlevel	find the previous and current system runlevel.	runlevel
printenv	print all or part of environment	printenv
env	run a program in a modified environment	env
hostname	show or set the system's host name	hostname ← show the system's host name
I recommend uname -n for check hostname.
hostname NEWHOSTNAME ← set the system's host name
uname	print system information	uname -a ← print all information (=uname --all)
uname -n ← show the system's host name (=uname --nodename)
locale	Get locale-specific information.	locale
locale -a

프로세스 관리

명령어	설명	예시
ps	report a snapshot of the current processes	ps aux
ps aux	grep XXX	awk '{print $2}'
ps auxwf
ps auxwf	grep XXX
pgrep	look up processes based on name and other attributes	pgrep -f 'bash'
pgrep -lf 'bash' ← output with process name
pgrep -f 'bash	xargs kill
pstree	display a tree of processes	pstree -a
pidof	find the process ID of a running program	pidof httpd
/bin/kill $(/sbin/pidof qmail-popup)
kill	send a signal to a process	kill -9 PID ← -9 or -KILL = force-quit
pkill	signal processes based on name and other attributes	pkill -f 'bash'
pkill -u user1
pkill java
pkill -f jar
killall	kill processes by name	killall vi
killall -i vi ← -i = interactively
killall -HUP kterm
killproc
lsof	list open files	lsof -i
lsof -i -P ← no port names
lsof -i :80,443 ← Which process is using Port 80,443
Ctrl + C	Stop running process
Ctrl + Z	Suspend running process	Move Running Process to Background
1. ctrl + z
2. jobs
3. bg
4. disown %JOBID
jobs	The first form lists the active jobs.
fg	Resume jobspec in the foreground
bg	Resume each suspended job jobspec in the background	jobs -l ← List job
nohup	run a command immune to hangups, with output to a non-tty	nohup command.sh &
disown		disown %JOBID
nice	run a program with modified scheduling priority	nice -n 19 test.sh
nice -n 19 ionice -c 3 CMD
nice -n 19 ionice -c 2 -n 7 COMMAND
renice	alter priority of running processes	renice 19 -p PID
you can check the nice with "top" or "ps alx"
ionice	sets or gets process io scheduling class and priority	ionice -p PID ← check
ionice -c 3 -p PID
nice -n 19 ionice -c 2 -n 7 COMMAND

스케줄

명령어	설명	예시
crontab	maintain crontab files	crontab -l ← -l = list user's crontab
crontab -u USER -l
crontab -e ← -e = edit user's crontab
crontab -u USER -e
at	queue jobs for later execution	echo "/sbin/shutdown -h now"
at -t 200902302100
atq	lists the user's pending jobs	atq
atrm	delete jobs for later execution	atrm JOBID
watch	execute a program periodically, showing output fullscreen	watch ntpq -p ← By default, the program is run every 2 seconds
watch -n 1 ntpq -p ← 1 seconds interval
-d = highlight the differences between successive updates

시스템 ETC

명령어	설명	예시
ntpupdate	set the date and time via NTP	ntpupdate -b -u IP
-b = Force the time(step mode)
-u = If you are running ntpd, "-u" must be added
history	GNU History Library	history
history 5 ← lists only the last 5 lines
HISTSIZE=1000
HISTTIMEFORMAT="%Y/%m/%d %H:%M:%S"
which	locate a command	which ls
strace	trace system calls and signals	strace -t php test.php
strace -t -o test.txt php test.php
-t = each line of the trace with the time of day
ltrace	A library call tracer	ltrace -o test.txt wget http://example.com/
ltrace -p PID
ltrace -p 3365
script	make typescript of terminal session	script -afq $LOG

파일 및 디렉토리 명령어

파일 명령어

명령어	설명	예시
ls	list directory contents	ls -ltrh ← -r = reverse order while sorting
-h = with -l, print sizes in human readable format
ls -ltrh	less
cp	copy files and directories	cp -p SRC DES
cp -pr SRC/ DES/ ← -r, -R = copy directories recursively
cp -f SRC DES ← -f, --force
mv	move (rename) files	mv file1 file2
mv dir1 dir2
mv file1 file2 DIR
rename	rename multiple files	rename 's/(.변경하고자 하는 text)/(.변경할 text)' (찾을 파일)
rename 's/.txt/.c/' *.txt ← *.txt 파일을 모두 *.c파일로 변경하기
rename -n 's/test/ttt/' *.txt ← -n = 변경될 파일 미리 출력 가능(검증용)
rename -v 's/test/ttt/' *.txt ← -v = 변경 및 변경된 파일 출력
rm	remove files or directories	rm -rf TARGET ← -r, -R = remove directories
touch	change file timestamps	touch file1
touch -d "2021/10/20 13:00:00" file1
ln	make links between files	ln -s SRC DES
unlink		unlink DES
wc	print newline, word, and byte counts for each file	wc -l ← -l, --lines = print the line counts
tree	list contents of directories in a tree-like format	tree -Dpuga /etc
col	filter reverse line feeds from input	man ifconfig

디렉터리 명령어

명령어	설명	예시
pwd	print name of current/working directory	pwd
cd	Change the current directory	cd ~
cd ..
pushd	Adds a directory to the top of the directory stack	pushd /var/log
pushd `pwd`
popd	Removes entries from the directory stack	popd
dirs	displays the list of currently remembered directories	dirs -v
mkdir	make directories	mkdir -p /tmp/test1/test2/ ← make parent directories as needed
mkdir -m 700 /home/user01/.ssh
rmdir	remove empty directories
If you want to delete directory, you must use “rm -r DIR”	rmdir DIR

파일 내용 접근 명령어

명령어	설명	예시
more	file perusal for crt viewing
less	opposite of more	crontab -l
view	Start in read-only mode
cat	concatenate files and print on the standard output	cat /dev/null > access.log
tail	output the last part of files	tail -n 50 a.txt ← output the last N lines
tail -f /var/log/messages
tailf	follow the growth of a log file	head -n 100 a.txt ← -n, --lines
head	output the first part of files
diff	compare files line by line	diff --suppress-common-lines --side-by-side File1 File2
diff -r dir1 dir2 ← When comparing directories, recursively compare
sdiff	side-by-side merge of file differences	sdiff -s File1 File2 ← -s = Do not print common lines
sdiff -s -w 200 File1 File2
colordiff
vimdiff		vimdiff File1 File2
vim -d File1 File2

검색

명령어	설명	예시
grep	print lines matching a pattern	grep WORD FILE
grep -Ev "^#	^$" xxx.tx
grep . ifcfg-eth* ← check filename and contents
grep -r PATTERN --include="*.txt" DIRECTORY ← -r = recursive
egrep	egrep is the same as grep -E	egrep "aaa
find, xargs	search for files in a directory hierarchy	find . -name "txt"

유저 관리(Administration)

유저

명령어	설명	예시
useradd	create a new user or update default new user information	useradd -G wheel USER1
adduser	add a user to the system
whoami	print effective userid	whoami
w	Show who is logged on and what they are doing	w
who	show who is logged on	who
userdel	delete a user account and related files	userdel -r USER ← -r, --remove = Files in the user's home directory will be removed
vipw	edit the password, group, shadow-password or shadow-group file	vipw ← edit /etc/passwd
vipw -s ← edit /etc/shadow
passwd	change user password	passwd -S USER01 ← check about the status of the password
passwd -l USER01 ← locc the user
passwd -u USER01 ← unlock
chpasswd	update passwords in batch mode	echo USER01:password
chage	change user password expiry information	chage -l USER ← check
chage -M 90 USER ← the password expires day set 90 days
usermod	modify a user account	usermod -g GROUP USER
usermod -l NEW_USERNAME OLD_USERNAME ← change username
usermod -u UID USER ← change UID
chsh	change login shell	chsh -s /bin/bash ← changing shell
getent	get entries from Name Service Switch libraries	getent passwd ← you can check LDAP users
pam_tally2	The login counter (tallying) module	pam_tally2 -u USER ← check
pam_tally2 -u USER --reset ← reset

그룹

명령어	설명	예시
groups	print the groups a user is in	groups
groups USERNAME
groupadd	create a new group	groupadd -g GIP GROUP
groupadd -g 1100 dev
addgroup	add group to the system	addgroup [--gid ID] group
groupdel	delete a group	groupdel GROUP
groupmod	change USER's GID	groupmod -g GID GROUP
groupmod -g 1501 testgroup1
chgrp	change the Group of the file	chgrp -R GROUP FILE
vigr	edit the password, group, shadow-password or shadow-group file

파일 권한

명령어	설명	예시
chmod	change file mode bits	chmod 777 TARGET
chmod u+s PROGRAM ← add SSUID(Set User ID)
chown	change file owner and group	chown USER FILE
chown USER:GROUP FILE

유저 ETC

명령어	설명	예시
finger	user information lookup program	finger USER01
su	change user ID or become superuser	su - ← change root user
sudo su - USER -s /bin/bash
sudo	execute a command as another user	sudo -u USER COMMAND
id	print real and effective user and group IDs	id USERNAME
last	show listing of last logged in users	last -5 ← last 5 logged in users
last USER
lastlog	reports the most recent login of all users or of a given user	lastlog
umask	set file mode creation mask	umask 022 ← default 666-022=644 (rw-r--r--)

네트워크

네트워크

명령어	설명	예시
ip	show / manipulate routing, devices, policy routing and tunnels	ip a(=addr) ← print ip address
ip r(=route) ← show IP routing
ss	another utility to investigate sockets	ss -lt ← list all listening TCP connections
ss -ua ← List all UDP connections
ss -ltp ← process name with listening TCP
ifconfig	configure a network interface	ifconfig ← check ip
ifconfig -a ← -a = display all interfaces
ifconfig eth0 up or d
ifdown	take a network interface down	ifdown eth0
ifup	bring a network interface up	ifup eth0
route	show / manipulate the IP routing table	route ← show the IP routing table
rout add-net 192.168.10.0 netmast 255.255.255.0 gw 10.51.0.1
ethtool	Display or change ethernet card settings	ethtool eth0
ethtool -s eth0 speed 100 duplex full autoneg off
mii-tool	view, manipulate media-independent interface status	mii-tool eth0
arp	manipulate the system ARP cache	arp -n
arp -an ← a = show the entries of the specified hosts
arp -d 192.168.xx.xx ← delete arp
tcpdump	dump traffic on a network	tcpdump -n port 80 -i any
tcpdump -n not arp and not port 123 and not port 22
tcpdump -r /tmp/20210121.pcap ← -r = read packets from file

네트워크 연결 확인

명령어	설명	예시
ping	send ICMP ECHO_REQUEST to network hosts
traceroute	print the route packets trace to network host	ping -c 5 -s 1500 192.168.0.1
tracepath	traces path to a network host discovering MTU along this path	traceroute -n 192.168.0.10
traceroute -T -p 80 192.168.0.10 ← -T = TCP
nmap	Network exploration tool and security / port scanner	nmap google.com ← check TCP
nmap -Pn -sT -p 22 xx.xx.xx.xx ← check firewall
nmap -p 443 www.google.com
nc
netcat	Concatenate and redirect sockets	nc 192.168.0.10 80 22 ← check TCP
nc -vz 192.168.0.10 1-1023 ← port scan
httping	measure the latency and throughput of a webserver

DNS

명령어	설명	예시
dig	DNS lookup utility	dig [@global-server] [domain] [q-type]
dig @8.8.8.8 google.com any
nslookup	query Internet name servers interactively	nslookup -type=any google.com 8.8.8.8
host	DNS lookup utility	host [-t type] [server]
host -t mx gmail.com 8.8.8.8
whois	client for the whois service	whois google.com
nscd	name service cache daemon	nscd -i hosts ← clear cache

연결

명령어	설명	예시
telnet	user interface to the TELNET protocol	telnet IP PORT
ssh	OpenSSH SSH client (remote login program)	ssh USER@IP
ssh xx.xx.xx.xx sudo /sbin/reboot
scp	secure copy (remote file copy program)	scp -rp /tmp/test1/ user1@192.168.0.10:/tmp/test2/
rsync	a fast, versatile, remote (and local) file-copying tool	rsync -avz --delete /home/user1/ /tmp/user1.bk/ ← rsync “/” is very important.
rsync -e ssh -avz --delete /home/user1/ user2@192.168.0.2:/home/backup/server1/home/user1/
ssh-keygen	authentication key generation, management and conversion	ssh-keygen -t rsa ← generate RSA key pair
ssh-keygen -R HOST
← removes all keys belonging to hostname from a known_hosts file
ssh-copy-id	use locally available keys to authorise logins on a remote machine	ssh-copy-id USER@xx.xx.xx.xx

HTTP

명령어	설명	예시
curl	transfer a URL	curl -I http://www.example.com/ ← Only Header
curl -i http://www.example.com/ ← Header and Body
wget	The non-interactive network downloader	wget http://google.com/
wget -e http_proxy=xx.xx.xx.xx:8080 http://example.com/

하드웨어

하드웨어

명령어	설명	예시
dmesg	print or control the kernel ring buffer	dmesg
lsusb	List USB devices	lsusb
lspci	list all PCI devices	lspci
nproc	print the number of processing units available	nproc
inxi	Display info about all hardware	inxi -Fxz
hwinfo	Display info about all hardware	hwinfo --short
lshw	Display info about all hardware	lshw --short
lshw -C cpu ← display all CPU info
lshw -short -C memory
lshw -short -C disk
lshw -C network
lscpu	Display all CPU info	lscpu

모듈

명령어	설명	예시
lsmod	show the status of modules in the Linux Kernel	lsmod
modinfo	show information about a Linux Kernel module	modinfo MODULENAME
modinfo bnx2
insmod	insert a module into the Linux Kernel
rmmod	remove a module from the Linux Kernel
modprobe	add and remove modules from the Linux Kernel

디스크 유틸(Utilities)

HDD

명령어	설명	예시
du	estimate file space usage	du -sh *
du -sh dir/
du -h --max-depth=1
fuser	identify processes using files or sockets	fuser -mv /mnt/test ← check
fuser -mvk /mnt/test ← -k = kill processes
chroot	run command or interactive shell with special root directory
hdparm	get/set hard disk parameters
dumpe2fs	dump ext2/ext3/ext4 filesystem information
badblocks	search a device for bad blocks

파티션

명령어	설명	예시
df	report file system disk space usage	df -h ← -h = print sizes in human readable format
df -BM ← megabyte unite
sfdisk	partition table manipulator for Linux	sfdisk -l ← -l = list the partitions of a device
fdisk	manipulate disk partition table	fdisk -l ← -l = list the partition tables
fdisk -l /dev/sdb
gdisk	Interactive GUID partition table (GPT) manipulator
parted	a partition manipulation program	parted -l ← check partitions
parted /dev/mapper/mapth0
lsblk	list block devices	lsblk
e2label	Change the label on an ext2/ext3/ext4 filesystem

Swap

명령어	설명	예시
mkswap	set up a Linux swap area
swapon	enable devices and files for paging and swapping	swapon -s ← check
swapon -a
swapon /dev/xvda3
swapoff	disable devices and files for paging and swapping	swappoff -a

파일 시스템

명령어	설명	예시
mkfs	build a Linux filesystem
#you must umount the device before mkfs)	mkfs -t xfs /dev/sdb1
mkfs -t ext4 /dev/sdb2
mkfs.xfs
mkfs.ext4
mkfs.ext3	#you must umount the device before mkfs.	mkfs.ext4 /dev/sdb1
mkfs2fs	create an ext2/ext3/ext4 filesystem
#you must umount the device before mkfs	mke2fs /dev/sdb1 ← ext2
tune2fs	adjust tunable filesystem parameters on ext2/ext3/ext4 filesystems	tune2fs -l /dev/mapper/mpath0 ← -l = list the contents of the filesystem superblock
tune2fs -i 0 -c 0 /dev/mapper/mpath0 ← -i = interval, -c = mount count
fsck	check and repair a Linux filesystem you must umount the device before fsck. for example single usermode and umount. ('shutdown -r -F now' is force fsck after reboot.)	fsck -p /dev/sda1 ← -p = automatically repair the file system
fsck.ext4	check and repair a Linux filesystem
e2fsck	check a Linux ext2/ext3/ext4 file system
resize2fs	ext2/ext3/ext4 file system resizer	resize2fs /dev/testvg/lvol0

데이터

명령어	설명	예시
dd	convert and copy a file	dd if=/dev/zero of=test_10M bs=1M count=10
sync	flush file system buffers
shred	overwrite a file to hide its contents, and optionally delete it

마운트

명령어	설명	예시
mount	mount a filesystem	mount /mnt/test /dev/sda1
mount -o remount /dev/sda1
umount	unmount file systems	umount /mnt/test
umount -f /mnt/test ← -f = force unmount(in case of an unreachable NFS system)

성능

성능

명령어	설명	예시
top	display Linux processes	top -b -n 4 -d 5 ← interval 5 sec, 4 times
sar	Collect, report, or save system activity information	sar -f /var/log/sa/sa16
sar (cpu, io)
sar -r (memory)
vmstat	Report virtual memory statistics	vmstat 1 ← interval 1sec (cpu, io, memory, swap)
vmstast 1 5 ← interval 1 sec, 5 times
iostat	Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.	iostat -xtk 1 (cpu, io) ← interval 1 sec
mpstat	Report processors related statistics.	mpstat -P ALL
w	Show who is logged on and what they are doing
free	Display amount of free and used memory in the system	free -m ← show output in MB
netstat	Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships	netstat -anp ← a = show both listening and non-listening sockets
netstat -rn ← -r = display the kernel routing tables
iotop	simple top-like I/O monitor	iotop -b -n 4 -d 15 ← interval 15 sec, 4 times
dstat	versatile tool for generating system resource statistics	dstat -taf

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• 출처 : https://cmdref.net/os/linux/command/index.html