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Crash bash, in case you ever want to for whatever reason

This is a very hackish way to do it that I'm mainly just posting for fun, and I guess technically can more accurately be said to result in undefined behavior. What the command does is tell the shell to treat libpng like it's a shell plugin (which it's most certainly not) and attempt to install a "png_create_read" command from the library. It looks for the struct with the information about the command; since it's always the command name followed by "_struct", it'll look for a symbol called "png_create_read_struct". And it finds it, since this is the name of one of libpng's functions. But bash has no way to tell it's a function instead of a struct, so it goes ahead and parses the function's code as if it was command metadata. Inevitably, bash will attempt to dereference an invalid pointer or whatever, resulting in a segfault.
This is sample output - yours may be different.
0

enable -f /usr/lib/libpng.so png_create_read

flarn2006 · 2021-10-09 05:22:52 22
Infinite loop ssh
This is sample output - yours may be different.
0

until ssh login@10.0.0.1; do echo "Nope, keep trying!"; fi; sleep 10; done

minnmass · 2021-09-29 14:53:55 60
Infinite loop ssh

Useful when you wait for a server to boot up.
This is sample output - yours may be different.
0

while true; do ssh login@10.0.0.1; if [[ $? -ne 0 ]]; then echo "Nope, keep trying!"; fi; sleep 10; done

FluffyBrick · 2021-09-29 12:54:17 23
Download SSL/TLS pem format cert from https web host
This is sample output - yours may be different.
1

openssl s_client -showcerts -connect google.com:443 </dev/null 2>/dev/null|openssl x509 -outform PEM > /tmp/google.com.cer

zhangtai · 2021-09-24 02:37:00 24
Add a DNS server on the fly

Since systemd-resolved was implemented, add a DNS server have become weirder and harder than before. With this command, you can add a DNS server on-the-fly tied to an specific interface
This is sample output - yours may be different.
1

sudo systemd-resolve --interface <NombreInterfaz> --set-dns <IPDNS> --set-domain mydomain.com

x3mboy · 2021-09-21 14:43:48 21
Windows telnet

Check if TCP port is reacheable Show Sample Output
This is sample output - yours may be different.
```
ComputerName     : ecample.com
RemoteAddress    : 192.168.1.59
RemotePort       : 443
InterfaceAlias   : SRV-37
SourceAddress    : 192.168.1.10
TcpTestSucceeded : True
```
1

Test-NetConnection -ComputerName example.com -Port 443

EBAH · 2021-09-16 16:11:04 19
Superfast portscanner
This is sample output - yours may be different.
1

time seq 65535 | parallel -k --joblog portscan -j9 --pipe --cat -j200% -n9000 --tagstring '\033[30;3{=$_=++$::color%8=}m' 'nc -vz localhost $(head -n1 {})-$(tail -n1 {})'

wuziduzi · 2021-09-14 16:15:51 27
Clear Cached Memory on Ubuntu

Clear Cached Memory on Ubuntu based distributions, and also display memory status. Please do not use this on a production machine unless you really really know what you are doing. Echo 3 is a kinder way of purging the memory, you can also use 'echo 2' or 'echo 1' if #1 You know what you are doing, and #2 refer to number 1 :-)
This is sample output - yours may be different.
0

sudo free && sync && sudo echo 3 | sudo tee /proc/sys/vm/drop_caches

tg0000 · 2021-09-13 16:45:20 14
Check a directory of PNG files for errors

Useful for checking if a large number of PNG files was downloaded successfully by verifying the built-in CRC checksum. For incomplete files, the command will print: "00002309.png EOF while reading IDAT data ERROR: 00002309.png" The process is very fast; checking 21,000 files of 5MB in size took only five minutes on a 2011 Intel mobile dual-core.
This is sample output - yours may be different.
0

ls *.png |parallel --nice 19 --bar --will-cite "pngcheck -q {}"

Negate · 2021-09-05 00:37:07 38
Banner Grabber
This is sample output - yours may be different.
1

bash -c 'exec 3<>/dev/tcp/google.com/80; echo EOF>&3; cat<&3'

wuziduzi · 2021-09-03 00:18:05 21
generate pem cert from host with ssl port
This is sample output - yours may be different.
0

openssl s_client -connect HOSTNAME.at:443 -showcerts </dev/null 2>/dev/null | openssl x509 -outform PEM > meinzertifikat.pem

dbiesecke · 2021-09-01 14:05:36 22
Get all lines that start with a dot or period

Read a file or standard input and only outputs lines that start with a dot or period "." Show Sample Output
This is sample output - yours may be different.
```
.config
```
0

grep '^\.' file

bugmenot · 2021-08-22 16:04:11 38
Store Host IP in variable
This is sample output - yours may be different.
-1

export IP="$(hostname -I | awk '{print $1}')"

wuziduzi · 2021-08-10 03:48:21 26
Download mp3 files linked in a RSS podcast feed

Directly download all mp3 files of the desired podcast
This is sample output - yours may be different.
0

curl http://radiofrance-podcast.net/podcast09/rss_14726.xml | grep -Eo "(http|https)://[a-zA-Z0-9./?=_%:-]*mp3" | sort -u | xargs wget

pascalv · 2021-08-09 13:40:26 45
Color STDERR in output

This command will take the output of a command and color any STDERR output as a different color (red outline in this case) Show Sample Output
This is sample output - yours may be different.
```
This is a normal line
This is an error line # this is red outlined
```
3

./errorscript.sh 2> >(echo "\e[0;41m$(cat)\e[0m")

tyzbit · 2021-08-08 14:28:50 36
Combine multiple images into a video using ffmpeg

The -start_number can be ignored if sequence starts with 0, otherwise use first number in sequence
This is sample output - yours may be different.
0

ffmpeg -start_number 0053 -r 1/5 -i IMG_%04d.JPG -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4

alikhalil · 2021-08-01 12:39:44 53
premiumize - create a ddl & save the URL in variable MYLINK
This is sample output - yours may be different.
1

MYLINK=$(curl 'https://www.premiumize.me/api/transfer/directdl?apikey=dzx3rqwrxme8iazu' \ -H 'accept: application/json' \ -H 'Content-Type: application/x-www-form-urlencoded' --data-raw 'src='$URL | jq -r '.content[] | .link' )

dbiesecke · 2021-07-25 09:20:31 30

Offcloud - add a link as remote download

You will get an json respond if all is fine Show Sample Output

curl 'https://offcloud.com/api/remote?key=XXXXXX' \ -H 'accept: application/json' \ -H 'Content-Type: application/x-www-form-urlencoded' --data-raw "url=$MYLINK&remoteOptionId=XXXXX"

dbiesecke · 2021-07-25 09:19:14 50

checks size of directory & delete it if its to small

only simple example how to combine rclone & jq Show Sample Output
This is sample output - yours may be different.
```
Transferred:              0 / 0 Byte, -, 0 Byte/s, ETA -
Errors:                 1 (retrying may help)   
Deleted:                0 (files), 3 (dirs)
Elapsed time:        14.2sTransferred:                    0 / 0 Byte, -, 0 Byte/s, ETA -
Errors:                 1 (retrying may help)
Deleted:                0 (files), 3 (dirs)
Elapsed time:        14.2s
2021/07/25 11:14:04 Failed to purge: unlinkat /mnt/anime/Anime/Fansub/Basquash! (2009): input/output error
```
1

for i in *; do test -d "$i" && ( rclone size "$i" --json -L 2> /dev/null | jq --arg path "$i" 'if .bytes < 57462360 then ( { p: $path , b: .bytes}) else "none" end' | grep -v none | jq -r '.p' | parallel -j3 rclone purge "{}" -v -P ); done

dbiesecke · 2021-07-25 09:16:03 23
Get a range on line with sed (first two)

Get the two first lines of a file and quit. Show Sample Output
This is sample output - yours may be different.
```
first-line
second-line
```
2

sed -n '1,2p;3q' file

bugmenot · 2021-07-16 07:29:15 29
Remove all the characters before last space per line including it
This is sample output - yours may be different.
1

echo 'The quick brown fox jumps over the lazy dog' | sed 's|.* ||'

bugmenot · 2021-07-16 07:17:08 21
Get line number 12 (or n) from a file

Extracts only file number 12 from file. It's meant for text files. Replace 12 with the number you want. First line starts at 1 not 0. We use q on next line so doesn't process any line more.
This is sample output - yours may be different.
2

sed -n '12p;13q' file

bugmenot · 2021-07-15 20:13:05 19
Replace all forward slashes with backward slashes

Use -i option to edit directly a file: sed -i 's|\/|\\|g' file Show Sample Output
This is sample output - yours may be different.
```
\usr\bin\
```
3

echo '/usr/bin/' | sed 's|\/|\\|g'

bugmenot · 2021-07-15 20:09:34 36
Replace all backward slashes with forward slashes

Use -i to edit file directly: sed -i 's|\\|\/|g' file Show Sample Output
This is sample output - yours may be different.
```
C:/Windows/
```
2

echo 'C:\Windows\' | sed 's|\\|\/|g'

bugmenot · 2021-07-15 20:07:37 48
Remove all the characters after last space per line including it

It his example removes ' dog', last space included. Show Sample Output
This is sample output - yours may be different.
```
The quick brown fox jumps over the lazy
```
0

echo 'The quick brown fox jumps over the lazy dog' | sed 's|$.*$ .*|\1|'

bugmenot · 2021-07-15 20:01:32 38
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list block devices

Shows all block devices in a tree with descruptions of what they are.

Blink Caps Lock on HDD activity

Some computers these days don't have an HDD activity light, but they still have a useless caps-lock, so why not re-purpose that light to show HDD activity? Requires setleds and dstat and probably needs to run as root.

Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Tree based ps view "painted" by ccze

Find jpeg images and copy them to a central location

Use if you have pictures all over the place and you want to copy them to a central location Synopsis: Find jpg files translate all file names to lowercase backup existing, don't overwrite, preserve mode ownership and timestamps copy to a central location

Convert seconds to [DD:][HH:]MM:SS

Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Convert seconds to [DD:][HH:]MM:SS

Increase SCT of external USB disk enclosure to one hour.

So I had this 2TB Seagate external disk/USB enclosure which by default would spin-down its internal drive (it enters a standby mode) after four minutes of inactivity.. Spinning-up the inactive drive was an annoying delay when accessing files and also it severely interfered with NFS.. SCT stands for "Standby Condition Timer". To completely disable SCT: $ sdparm --clear STANDBY -6 /dev/sdb To return to original (default) SCT settings: $ sdparm -D -p 0x1a -6 /dev/sdb To verify the settings (before and after): $ sdparm -a /dev/sdb No need for vendor-provided MSWIN tools, etc.

Check reverse DNS

I'm just a simple programmer. I find dig too verbose. host tells me alias(es) and IP address in a quick to grok format with nothing special to remember for input parameters. With thanks to http://www.cyberciti.biz/faq/how-to-test-or-check-reverse-dns/

String to binary

Cool but useless.

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