linux-commands.md

useful linxu commands:

SSH

ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -i ~babaYaga-conf/weaver_sample.pem ec2-user@

SSH debug mode (level 3)

ssh -vvv

SSH delays:

http://injustfiveminutes.com/2013/03/13/fixing-ssh-login-long-delay/

ssh -o GSSAPIAuthentication=no

history without the numbers

history | cut -c 8- |grep log

CAT all the files in a directory. Generates a lot of Read IO

find . -name "*.log" -print | xargs cat

find busy ports

sudo lsof -i TCP -P

List large directories:

du -m | sort -n

List large files:

ls -Slhr
open -a Smultron <file_name>

watch for changes

watch ls -l

##list ports:

lsof -i -P   # list open ports
lsof -i -P | grep LISTEN
netstat -a

Disk Usage

DiskStation> du -hc -d 1 .

Estimate disk size on directories:

du -d 2 -m -P -x -c

Disk usage:

[root@itmm /]#  du -hc --max-depth=1 .
16K     ./lost+found
11M     ./boot
428K    ./dev
du: cannot change to directory `./proc/5629/fd': No such file or directory
du: `./proc/5681/fd/4': No such file or directory
923M    ./proc
12G     ./var
14M     ./tmp
18M     ./etc
17M     ./root

df -h

disable service:

chkconfig iptables off
[root@rcc-pok-rem-02 bin]# chkconfig --list iptables
iptables        0:off   1:off   2:off   3:off   4:off   5:off   6:off

Time synchronize:

[root@rcc-pok-rem-02 ~]# ntpdate pokgsa.ibm.com
13 Feb 10:48:40 ntpdate[15298]: adjust time server 9.56.248.25 offset 0.000660 sec
[root@rcc-pok-rem-02 ~]# vi /etc/ntp.conf

[root@rcc-pok-rem-02 ~]# service ntpd start
Starting ntpd:                                             [  OK  ]
[root@rcc-pok-rem-02 ~]# date
Fri Feb 13 10:50:05 EST 2009
Synchronize
[root@rcc-pok-rem-02 ~]# ntpd -q
[root@rcc-pok-rem-02 ~]# date
Fri Feb 13 10:51:19 EST 2009

list IPv4 IP addresses and their interfaces:

ip -4 a