All processes, with params + hierarchy
ps auxww -H
Show all ruby-related PIDs and processes
pgrep -fl ruby
What is a process doing?
strace -f -p $PID
What files does a process have open? (also nice to detect ruby version of a process)
lsof -p $PID
Flavors of kill
kill xxxxkill xxxx yyyy zzzzpkill <name of process>pkill -f <word in process name>
Keep an eye on a process
watch 'ps aux | grep ruby'
How much mem is free?
free -mcat /proc/meminfo
Are we swapping? First line is avg since boot
vmstat 1
List the top 10 memory hogs
ps aux --sort=-resident|head -11
Detect OOM and other bad things
for i in messages kern.log syslog; do egrep -i "s[ie]g|oo(m|ps)" /var/log/$i{,.0}; done
Disable OOM killer for a process
echo -17 > /proc/$PID/oom_adj
Check reads/writes per disk
iostat -xnk 5
Files (often logs) marked for deletion but not yet deleted
lsof | grep delete
Overview of all disks
df -h
Usage of this dir and all subdirs
du -hs
Find files over 100MB
find . -size +100M
Low hanging fruit for free space. Check /var/log too...
ls -al /tmp
Find files created within the last 7 days
find . -mtime -7
Find files older than 14 days
find . -mtime +14 -type f -name '*.gz'
Delete files older than 14 days
find *.gz -mtime +14 -type f -exec rm {} \;
Monitor a log file for an IP or anything else
tail -f file.log | grep 192.168.1.1
Generate a large file (count * bs = total bytes)
dd if=/dev/zero of=file.txt count=1024 bs=102
TCP sockets in use
lsof -nPi tcp
Get IP/Ethernet info
ip addrifconfig
host <=> IP resolution
host 192.168.1.1host MyRouter
Curl, display headers (I), follow redirects (L)
curl -LI http://google.com
Traceroute with stats over time (top for traceroute) Requires install
mtr google.com
Traceroute using TCP to avoid ICMP blockage
tcptraceroute google.com
List any IP blocks/rules
iptables -L
Drop any network requests from IP
iptables -I INPUT -s 66.75.84.220 -j DROP
Show traffic by port
iftop
Show all ports listening with process PID
netstat -tlnp
D/L speed test (don't run in prod! :)
wget cachefly.cachefly.net/100mb.test -O /dev/null
Start a screen session as the current user
screen -x
Join/re-attach to a screen session
screen -r
Record a terminal session
script filename.out 2> filename.timing
Playback a recorded terminal session
scriptreplay filename.timing filename.out
Run Previous command as root
sudo !!
Change to last working dir
cd -
Run something forever
while true;do ruby ghetto.rb;done
tail all queries hitting mysql. Learn more
pt-query-digest --processlist h=localhost --print --no-report --user xxxx --password *****
Connect to production mysql locally on port 3307 via ssh Learn More
ssh -L 3307:localhost:3306 user@hostname -N