Command Line Magic

mping (melody ping) will make an audible ping sound(remove headphones) pitched according to the latency. Ex: mping domains.au mping(){ ping $1|awk -F[=\ ] '/me=/{t=$(NF-1);f=3000-14*log(t^20);c="play -V0 -q -n synth 1 pl " f " vol 1 reverb -w ";print $0;system(c)}';}

sudo tune2fs -m0.2 /dev/sda1 # Running out of space on that 1TB drive? On Linux, the ext[234] filesystems reserve 5% of the space by default to only used by the root user, that's 50GB! You can reduce it to 0.2%

zless, zgrep, zcat, zdiff # There are helper commands for dealing with compressed files (gz, bz2 and xz). They have a z, bz or xz prefix. For instance, you can use zless like this zless access_log.gz to view it the same way you would with less. Others work similarly.

find ${PATH//:/ } -type f -maxdepth 1 -perm /6000 -ls # Find all the programs in path directories with suid or sgid bits set. Of course you probably just want to do this on the whole filesystem.

df -BG # List the file systems so that their space used/available is shown in gigabytes. This is more consistent than using just -h to show human readable. Good for if you have several and want to compare.

sort -V ipv4addrs.txt # In GNU sort, you can use -V (version sort) to also sort IPv4 addresses numerically according to each octet. For IPv6, try using ipv6calc --addr2fulluncompaddr first to normalize the addresses and pass to a plain sort.

echo -n pentacosiomedimni | wc -m # Check the length of a word in terms of it's character count. Although this word doesn't contain unicode characters, using the -m option would give you the expected answer if it did.

yes "$(seq 231 -1 16)" | while read i; do printf "\x1b[48;5;${i}m\n"; sleep .02; done # Make colorful gradients in your shell

yes $'\U1F427' | head -29 # Happy Birthday Linux!

date +%j # Today is International Bad Programmer's Day

grepcidr 2102:306:146e:f5d0::/64 /var/log/secure # Use a CIDR network format aware version of grep to search for hits from IPs within the IPv6 range 2102:306:146e:f5d0::/64

seq 2457 7542 | grep 2 | grep 4 | grep 5 | grep 7 # Find all potential 4 digit combinations that only have one of each number 2, 4, 5, and 7 for a CTF game.