CLI Tools
pdsh¶
Used to run commands to multiple nodes at once. By default uses /etc/genders to determine the hosts to run the commands on.
dshbak¶
Often used in conjunction with pdsh to aggregate command output.
Text Only
$ pdsh -g gpu "echo hello" | dshbak -c
----------------
node-[001-032]
----------------
hello
strace¶
strace can be used to inspect the system calls being made by an application.
Text Only
$ strace -f cat /tmp/hello.txt |& egrep 'hello'
execve("/bin/cat", ["cat", "/tmp/hello.txt"], 0x7fffffffc1a0 /* 115 vars */) = 0
openat(AT_FDCWD, "/tmp/hello.txt", O_RDONLY) = 3
read(3, "hello world\n", 131072) = 12
write(1, "hello world\n", 12hello world
View listening ports¶
Bash
$ netstat -anv
Active Internet connections (including servers)
Proto Recv-Q Send-Q Local Address Foreign Address (state) rhiwat shiwat pid epid state options gencnt flags flags1 usscnt rtncnt fltrs
tcp4 0 0 127.0.0.1.8001 127.0.0.1.60348 ESTABLISHED 407878 146988 34323 0 00102 00000004 000000000027587a 00000080 01000900 1 0 000001
tcp4 0 0 127.0.0.1.60348 127.0.0.1.8001 ESTABLISHED 408300 146988 24807 24804 00102 00020000 0000000000275879 10180081 00080900 1 0 000001
tcp4 0 0 192.168.50.89.60347 140.82.113.5.443 ESTABLISHED 131072 132432 24807 24804 00102 00020000 0000000000275878 10180081 00080900 1 0 000001
tcp4 0 0 192.168.50.89.60344 149.137.136.16.443 ESTABLISHED 1511016 131768 24807 24804 00102 00020000 000000000027585b 10180081 00080900 1 0 000001
Text Only
$ sudo lsof -i -P -n | grep LISTEN
systemd 1 root 79u IPv4 116762 0t0 TCP *:111 (LISTEN)
rpcbind 2942 _rpc 4u IPv4 116762 0t0 TCP *:111 (LISTEN)
systemd-r 2947 systemd-resolve 13u IPv4 142435 0t0 TCP 127.0.0.53:53 (LISTEN)
sshd 3175 root 3u IPv4 273290 0t0 TCP *:22 (LISTEN)
rpc.statd 3329 statd 9u IPv4 18403 0t0 TCP *:35287 (LISTEN)
virt-expo 135395 root 9u IPv4 334360 0t0 TCP *:9411 (LISTEN)
node_expo 178456 node-exp 3u IPv4 593613 0t0 TCP *:9100 (LISTEN)
systemd_e 178515 systemd-exporter 3u IPv4 624258 0t0 TCP *:9558 (LISTEN)
uniq¶
Use uniq -c to get counts of each occurence. This is more commonly used like cat file.txt | sort | uniq -c.
sort¶
Can also use sort with -u, which is equivalent to sort | uniq.
Describe a file handle using lsof¶
This is from a useful gist here: https://gist.github.com/tonyc/1384523?permalink_comment_id=3334070