Commands by Mozai

Commands by Mozai (13)

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seconds since epoch to ISO timestamp

No need to use perl, awk, nor /usr/bin/date -- bash's "printf" builtin will do it. Show Sample Output
This is sample output - yours may be different.
```
2020-11-30T11:07:30
```
2

printf '%(%FT%T)T\n' 1606752450

Mozai · 2021-06-20 05:11:20 261
Convert JSON to YAML

Valid JSON is a subset of YAML; no transformation is necessary; however, YAML has many syntax features that are not valid JSON, so you can't do the reverse as easily.
This is sample output - yours may be different.
-8

cat data.json >data.yml

Mozai · 2013-04-25 04:09:58 7
sleep until X o'clock

pauses exactly long enough to wake at the top of the hour
This is sample output - yours may be different.
2

sleep $((3600 - ($(date +%s) % 3600) ))

Mozai · 2012-12-09 16:21:57 18
Quickly CD Out Of Directories

`up 3` will climb the directory tree by three steps. `up asdf` will do nothing, and returns exit code 1 as an error should.
This is sample output - yours may be different.
6

up() { [ $(( $1 + 0 )) -gt 0 ] && cd $(eval "printf '../'%.0s {1..$1}"); }

Mozai · 2012-06-15 17:10:45 6
convert from hexidecimal or octal to decimal

Bash can accept '0x' and '0' notation for hexidecimal and octal numbers, so you just have to output the values. Show Sample Output
This is sample output - yours may be different.
```
510 27
```
18

echo $((0x1fe)) $((033))

Mozai · 2011-12-06 02:00:42 16
Get number of users on a minecraft server

I'm flat-out surprised that minecraft directory services require servers install multiple modifications to their server code, when the directories could fetch this information on their own. Show Sample Output
This is sample output - yours may be different.
```
users: 12/30
```
1

(echo -e '\xfe'; sleep 1) |telnet -L $HOSTIP 25565 2>/dev/null |awk -F'\xa7' '$2 {print "users: "$2"/"$3;}'

Mozai · 2011-11-07 02:28:03 8
Retrieve the size of a file on a server

Downloads the entire file, but http servers don't always provide the optional 'Content-Length:' header, and ftp/gopher/dict/etc servers don't provide a filesize header at all.
This is sample output - yours may be different.
2

curl -s "$URL" |wc -c

Mozai · 2011-07-18 15:47:57 4
Generate a random password

Another password maker, for human-unfriendly passwords. '-base64' output will make sure it it can be typed on a keyboard, though the output string length will always be a multiple of 4. Show Sample Output
This is sample output - yours may be different.
```
+SQauy3iRL3W/eso
```
3

openssl rand -base64 12

Mozai · 2011-07-06 17:48:26 16
Check if commands are available on your system
This is sample output - yours may be different.
0

for c in gcc bison dialog bc asdf; do if ! which $c >/dev/null; then echo Required program $c is missing ; exit 1; fi; done

Mozai · 2011-06-27 12:54:02 4
List your interfaces and MAC addresses

Requires sysfs mounted on /sys - may only be useful for Linux systems. Could also use "printf '%-8s %s\n' $(basename $f) $(cat $f/address)" instead of echo. Show Sample Output
This is sample output - yours may be different.
```
eth0	00:1d:09:xx:xx:xx
lo	00:00:00:00:00:00
wlan0	00:22:fb:xx:xx:xx
```
4

for f in /sys/class/net/*; do echo -e "$(basename $f)\t$(cat $f/address)"; done

Mozai · 2011-05-19 22:38:46 4

Cheap iftop

Shows updated status in a terminal window for connections to port '80' in a human-friendly form. Use 'watch -n1' to update every second, and 'watch -d' to highlight changes between updates. If you wish for status updates on a port other than '80', always remember to put a space afterwards so that ":80" will not match ":8080". Show Sample Output

watch 'netstat -anptu |egrep "^Proto|:80 "'

Mozai · 2011-05-18 15:05:52 27

Tell local Debian machine to install packages used by remote Debian machine

(also works on Ubuntu) Copies the 'install,' 'hold,' 'deinstall' and 'purge' states of packages on the remote machine to be matched on the local machine. Note: if packages were installed on the local machine that were never installed on the remote machine, they will not be deinstalled by this operation.
This is sample output - yours may be different.
27

ssh remotehost 'dpkg --get-selections' | dpkg --set-selections && dselect install

Mozai · 2011-05-12 17:26:43 12
Generate soothing noise

Substitute 'brown' with 'pink' or 'white' according to your taste. I put this on my headphones when I'm working in an "open concept" office, where there are always three to five conversations going in earshot, or if I'm working somewhere it is "rude" of me to tell a person to turn off their cubicle radio.
This is sample output - yours may be different.
3

/usr/bin/play -q -n synth brown band -n 1200 200 tremolo 0.05 80

Mozai · 2011-04-26 19:37:08 6

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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Print a list of all hardlinks in the working directory, recursively

libpurple likes to hardlink files repeatedly. To ignore libpurple, use sed: | sed '/\.\/\.purple/d'

Search command history on bash

Very handy and time-saving. Do a 'ctrl+ r' on command prompt. You will see a "(reverse-i-search)`':" mark. Just type any sub-string of the command you want to search(provided you have used it sometime in the same session). Keep on searching by repeatedly pressing ctrl+r. Press enter once you get the desired command string.

Lvextend logical volume

this command extends your logical volume. then it does a resize2fs on it as well. added the -r switch to make it launch resize.

Generate a random password 30 characters long

According to the gpg(1) manual: --gen-random 0|1|2 count Emit count random bytes of the given quality level 0, 1 or 2. If count is not given or zero, an endless sequence of random bytes will be emitted. If used with --armor the output will be base64 encoded. PLEASE, don't use this command unless you know what you are doing; it may remove precious entropy from the system! If your entropy pool is critical for various operations on your system, then using this command is not recommended to generate a secure password. With that said, regenerating entropy is as simple as: $ du -s / This is a quick way to generate a strong, base64 encoded, secure password of arbitrary length, using your entropy pool (example above shows a 30-character long password).

Watch TCP, UDP open ports in real time with socket summary.

Redirect incoming traffic to SSH, from a port of your choosing

Stuck behind a restrictive firewall at work, but really jonesing to putty home to your linux box for some colossal cave? Goodness knows I was...but the firewall at work blocked all outbound connections except for ports 80 and 443. (Those were wide open for outbound connections.) So now I putty over port 443 and have my linux box redirect it to port 22 (the SSH port) before it routes it internally. So, my specific command would be: $iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 22 Note that I use -A to append this command to the end of the chain. You could replace that with -I to insert it at the beginning (or at a specific rulenum). My linux box is running slackware, with a kernel from circa 2001. Hopefully the mechanics of iptables haven't changed since then. The command is untested under any other distros or less outdated kernels. Of course, the command should be easy enough to adapt to whatever service on your linux box you're trying to reach by changing the numbers (and possibly changing tcp to udp, or whatever). Between putty and psftp, however, I'm good to go for hours of time-killing.

Resume scp of a big file

list txt files order by time

list all txt files order by time, newest first

View the latest astronomy picture of the day from NASA.

Substitute feh for the image viewer of your choice. display (part of imagemagick) seems to be a popular choice.

Sort content of a directory including hidden files.

This command sorts the content including hidden files in human readable format of the current directory.

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