Linux

-bash: warning: setlocale: LC_ALL: cannot change locale (ko_KR.UTF-8)

sudo vim /etc/locale.gen # uncomment ko_KR.UTF-8 line.
sudo locale-gen 
# logout and re-login

한글 나오게 하기

.bashrc에 export LANG=ko_KR.UTF-8

X에 한글글꼴이 없을 수 있음. 그러면 윈도우에 글꼴 몇개 가져다가/usr/share/fonts/ms/에 넣고

# cd /usr/share/fonts/ms
# mkfontscale
# ttmkfdir
# fc-cache
# chmod -R a+r /usr/share/fonts/msfont

이렇게 하면 됨. 글꼴파일 이름이 한글이어도 정상동작했고 firefox에서 자동으로 인식했음. 터미널에는 글꼴 없어도 export LANG만 가지고도 됨.여기참고했음. 나는 fonts.dir, fonts.cache-1같은것이 생기지 않았기 때문에 저 중에 무언가를 빼도 될것같기도 함.

gcc설치

yum groupinstall 'Development Tools'

selinux

• see /etc/sysconfig/iptables (if you cannot access port 80 at remote place)
  1. Modify that file or
  2. Use the system-config-firewall command
  3. if this is not a problem, see this CentOS wiki page
     • semanage port -a -t http_port_t -p tcp 81
• Use setenforce command instead of echo 0 > /selinux/enforce (Because just simple. no other reasons)
• ls -Z
• ps -ZC httpd
  • or ps -eZ

Base64 decode to file

perl -MMIME::Base64 -ne 'print decode_base64($_)' < file.txt > out

http://wvarner.blogspot.com/2008/06/base64-decode-to-file.html

core file

cat /proc/sys/kernel/core_pattern

https://superuser.com/questions/849099/where-does-ubuntu-14-04-drop-core-files

network issues

gateway ip

 $ route -n
 $ netstat -r -n
 $ ip route show 

gateway가 아예 안나올 때(via ~가 보이지 않는다거나 route에서 gateway가 *.*.*.*)가 있던데 이건 어떤 경우인지 모르겠다.
www.cyberciti.biz

ip route examples

 ip route add 192.168.1.0/24 dev eth0
 ip route add default via 192.168.1.254
 ip route delete 192.168.1.0/24 dev eth0

www.cyberciti.biz

ip collision detect : arp-scan

$ sudo apt-get install arp-scan
$ arp-scan -I eth0 -l | grep 192.168.1.42
 192.168.1.42 d4:eb:9a:f2:11:a1 (Unknown)
 192.168.1.42 f4:23:a4:38:b5:76 (Unknown) (DUP: 2)

askubuntu.com

When ifdown is not working

$ sudo ifconfig eth0 down

http://unix.stackexchange.com/a/50604/31363

flushing interface

ip addr flush dev enp2s0

http://askubuntu.com/a/875180/400331

Set DNS manually

/etc/resolvconf/resolv.conf.d/base

nameserver 8.8.8.8
nameserver 8.8.4.4

sudo resolvconf -u

askubuntu.com

add static routes in Ubuntu

# vi /etc/network/interfaces
...
up ip route add 192.168.0.0/24 

https://askubuntu.com/a/168037/400331

Flushing dhcp

dhclient -r

https://askubuntu.com/q/151958/400331

network configuration examples (ubuntu)

help.ubuntu.com

• Setting/changing the hostname
• Finding your network interface
• Disable network managers and/or wicd
• Configuring an interface
• Setting up a second IP address or Virtual IP address
• Howto set MTU for a connection
• Setting up DNS
• Wireless

etc

ssh

ssh alias

edit ~/.ssh/config

Host myremote             # any name for the host
HostName 192.168.178.05   # IP, .local, or hostname if defined
User username             # your username
Port 22                   # port to listen

and then, ssh myremote
http://askubuntu.com/questions/257472/host-alias-for-ssh askubuntu.com

sshd restart

# sudo service ssh restart

or

# /etc/init.d/ssh restart

https://www.cyberciti.biz/faq/howto-restart-ssh/

centos 7 sshd service not found

systemctl enable sshd.service
systemctl start sshd.service
systemctl status sshd.service

https://www.digitalocean.com/community/questions/centos-7-sshd-service-not-found

kill x-server (stop lightdm)

ctrl + alt + F1 : to switch terminal. cf) ctrl+alt+F7 to switch x-window

sudo service lightdm stop

or

sudo /etc/init.d/lightdm stop 
# or 
sudo service lightdm stop
# lightdm can be known by this.
cat /etc/X11/default-display-manager

askubuntu.com askubuntu.comaskubuntu.com

“Required key not available” when install 3rd party kernel modules

or after a kernel upgrade.
To resolve this, disable Secure Boot in UEFI(BIOS) settings.
askubuntu.com

my Ubuntu version

lsb_release -a

help.ubuntu.com

symbolic link의 chown

-h 옵션을 같이 쓸 것. no dereference option.

https://superuser.com/a/68688

sudo without password

sudo visudo

In the bottom of the file, type the follow:

username ALL=(ALL) NOPASSWD: ALL

https://askubuntu.com/a/147265/400331

Upgrade single package

apt-get install --only-upgrade <packagename>

https://askubuntu.com/a/44124/400331

boot partition full

먼저, 쓸데없이 설치되어 있는 커널 찾아본다.

sudo dpkg --list 'linux-image*' | grep ^ii | awk '{print $2}' | sort | egrep "[0-9]-generic" | head -n -3

(여기의 세번째 댓글이 출처)
내 현재 커널과(uname -r)상관 없으면 다 쓸데없는 커널이미지.

그 다음, 지운다. 잘 안되면, 강제로 한다.

sudo dpkg --remove --force-remove-reinstreq <packagename>

[1]
dependency가 있으면 어떤 패키지부터 지우라고 알려준다. 현재 커널과 상관없으면 다 지워도 된다.

기도하면서 재부팅.

temporary ssh/rsync server

가장 쉬운 방법은, 한쪽에서

/sbin/sshd -p 6789

하고, 다른쪽에서 그 포트로 접속하는 것. rsync도 해당 포트를 이용해서 하는 것이 가장 빠르다.

rsync -e 'ssh -P 6789' user@1.2.3.4:path/to

How to Rsync with non-standard SSH Port

ssh ternnel

터널링에 관한 자료들

• Local and Remote Port Forwarding Explained With Examples
• SSH from A through B to C, using private key on B
• How to use local and remote SSH port forwarding

 

discussion

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