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quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

On CentOS at least, date returns a boolean for the common date string formats, including YYYY-MM-DD. In the sample output, you can see various invalid dates returning 0 whereas a simple regex check would return 1 for the invalid dates. -d, --date=STRING display time described by STRING, not `now' The version of date on OS X does not appear to have this same option. Show Sample Output
This is sample output - yours may be different.
```
# if date -d 2006-10-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi
1

# if date -d 2006-40-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi
0

# if date -d 2006-13-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi
0

# if date -d 2006-11-31 >> /dev/null 2>&1; then echo 1; else echo 0; fi
0
```
0

if date -d 2006-10-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi

SteveGoossens · 2013-01-10 10:35:15 7
Convert HAML to HTML on file change

Monitors the current directory for changes to HAML files and converts them to HTML. Show Sample Output
This is sample output - yours may be different.
```
Setting up watches.
Watches established.
Setting up watches.
Watches established.
Setting up watches.
Watches established.
```
0

while true; do filechanged=$(inotifywait -e close_write,moved_to --format "%w%f" .); haml $filechanged -q --no-escape-attrs > ${filechanged/.haml/.html}; done

batandwa · 2013-05-01 21:15:26 8
Generate a random password 30 characters long

Use less random number resources and less commands
This is sample output - yours may be different.
0

head -c 24 /dev/urandom | base64

henix · 2013-09-28 16:32:47 7

Show all symlinks

shows you the symlinks in the current directory, recursively, but without following them Show Sample Output

find ./ -type l -print0 | xargs -0 ls -plah

jmorganwalker · 2014-03-20 20:36:39 7

Get puppet modules path
This is sample output - yours may be different.
0

puppet config print modulepath

narven · 2014-07-08 08:41:19 7

dynamically list open files for a given process name

us lsof, grep for any pid matching a given name such as "node". Show Sample Output

lsof -i -n -P | grep -e "$(ps aux | grep node | grep -v grep | awk -F' ' '{print $2}' | xargs | awk -F' ' '{str = $1; for(i = 2; i < NF; i++) {str = str "\\|" $i} print str}')"

hochmeister · 2015-02-14 23:24:00 10

Inverted cowsay

It's quite fun to invert text using "flip.pl" (ref: http://ubuntuforums.org/showthread.php?t=2078323 ). Slightly more challenging is to flip a whole "cowsay". :-) Show Sample Output
This is sample output - yours may be different.
```
$ echo Which way up? | flip.pl | cowsay | tac | sed -e "s,/,+,g" -e "s,\\\,/,g" -e "s,+,\\\,g" -e "s,_,-,g" -e "s,\^,v,g"
                ||     ||
                ||----w |
            (--)/       )/\/
         /  (oo)/-------
        /   v--v
 ------------------------ 
< ?dn &#654;&#592;&#653; &#613;&#596;&#305;&#613;&#653; >
 ------------------------ 
```
0

echo Which way up? | flip.pl | cowsay | tac | sed -e "s,/,+,g" -e "s,\\\,/,g" -e "s,+,\\\,g" -e "s,_,-,g" -e "s,\^,v,g"

mpb · 2016-04-08 11:41:44 28
Resize all images in folder
This is sample output - yours may be different.
0

mogrify -resize 25% *.jpg

swarzynski · 2016-06-10 18:14:08 10
Watch active calls on an Asterisk PBX
This is sample output - yours may be different.
0

watch -n 5 "asterisk -rx 'core show calls' | grep active"

vperalta · 2017-02-14 15:05:44 16
Delete huge numbers of files without intensive cpu load

I needed to find a command to delete huge numbers of files without intensive cpu load, that command does the job :) The purpose of "+" at then end of the line, tells rm to delete multiple files at once
This is sample output - yours may be different.
0

find <path> -type f -exec ionice -c3 rm {} +

tyjak · 2017-07-31 09:35:36 25
When you realise your AMI doesn't come with NTP
This is sample output - yours may be different.
0

AWS_DEFAULT_REGION="sa-east-1" jungle ec2 ls | grep midas | sort | cut -f4 | xargs -I {} ssh ubuntu@{} sudo apt-get install ntp -y

xymor · 2017-11-22 19:20:08 19

Get video information with ffmpeg

Fix for PHP Shell Exec: ffmpeg -i input.mp4 -f null /dev/null 2>&1 shell_exec("ffmpeg -i input.mp4 -f null /dev/null 2>&1"); Show Sample Output

This is sample output - yours may be different.

ffmpeg version N-90480-ge5819fa629 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 7.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth
  libavutil      56. 12.100 / 56. 12.100
  libavcodec     58. 16.100 / 58. 16.100
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 13.100 /  7. 13.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 1970-01-01T00:00:00.000000Z
    encoder         : Lavf53.24.2
  Duration: 00:00:05.31, start: 0.000000, bitrate: 1589 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1205 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:00.000000Z
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 384 kb/s (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:00.000000Z
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> wrapped_avframe (native))
  Stream #0:1 -> #0:1 (aac (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, null, to '/dev/null':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.10.100
    Stream #0:0(und): Video: wrapped_avframe, yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:00.000000Z
      handler_name    : VideoHandler
      encoder         : Lavc58.16.100 wrapped_avframe
    Stream #0:1(und): Audio: pcm_s16le, 48000 Hz, 5.1, s16, 4608 kb/s (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:00.000000Z
      handler_name    : SoundHandler
      encoder         : Lavc58.16.100 pcm_s16le
frame=  132 fps=0.0 q=-0.0 Lsize=N/A time=00:00:05.31 bitrate=N/A speed=11.8x
video:69kB audio:2988kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

ffmpeg -i input.mp4 -f null /dev/null

Dipo · 2018-11-06 13:44:46 446

WSL: Change the current directory converting a Windows path to a Linux Path

The Windows Subsystem for Linux (WSL) is a compatibility layer for running binary Linux executables natively in Windows. A folder such as "C:\Program Files (x86)\Common Files" is represented as "/mnt/c/Program Files (x86)/Common Files". This function allows you to change the current directory to a Windows folder. Show Sample Output
This is sample output - yours may be different.
```
function _cd() { local dir="$(sed -e 's~$[a-z]$:~/mnt/\L\1~gi' <<< "${*//'\'/"/"}" )"; if [ -d "$dir" ]; then cd "$dir"; fi; }

# quotes are necessary:
_cd 'C:\Program Files (x86)\Common Files';

# result: cd '/mnt/c/Program Files (x86)/Common Files'
```
0

function _cd() { local dir; dir="$(sed -e 's~$[a-z]$:~/mnt/\L\1~gi' <<< "${*//'\'/"/"}" )"; if [ -d "$dir" ]; then cd "$dir" || exit; fi; }

mikhail · 2019-06-06 17:53:28 41
Test python regular expressions

One can test their python regex matching using this shell function. for e.g. rgx_match "translate\s*$([0-9-.]+),([0-9-.]+)$" "translate(162.11517,76.817357)" ('162.11517', '76.817357')
This is sample output - yours may be different.
0

rgx_match() { python -c "import re; print re.search('$1','$2').groups()"; }

jyro · 2009-02-16 04:07:54 62
Show top-level subdirectories (zsh)
This is sample output - yours may be different.
0

ls -ld *(/)

H4rpy · 2009-02-27 08:30:16 5
Dns zone transfer

Perform a dns zone transfer (if is allowed on target dns server) and print result.
This is sample output - yours may be different.
0

host -la domain.com

servermanaged · 2009-03-28 12:15:16 5
Convert video type from mpg to wmv
This is sample output - yours may be different.
0

mencoder -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1000:vhq -oac mp3lame -lameopts br=98 -o output.wmv input.mpg

gombiuda · 2009-10-16 00:18:57 3
shell function to turn start and length in to a range suitable for using in cut.

for example: echo "..1234567." | cut -c $(range 3 7) yields 1234567
This is sample output - yours may be different.
0

range () { end=$(echo "$1 + $2 - 1" | bc); echo "$1-$end"; }

bartonski · 2009-11-12 22:53:08 3
print your iTunes App for iPhone/iTouch/iPad to show your friends which ones you have

omit "> ~/Desktop/MyAppList`date +%s.txt`" if you don't want to print it to a file on your desktop and instead only want to display to console created and tested on: ProductName: Mac OS X ProductVersion: 10.6.3 BuildVersion: 10D573 Show Sample Output
This is sample output - yours may be different.
```
1Password
3D Chess Free
Adobe? Ideas 1
AIM for iPad
Anaconda XL
Anagram
Arabic Alphabet Reference and Quiz
ascii2bin
[ cut for brevity ]
```
0

find ~/Music/iTunes/iTunes\ Media/. -name \*.ipa -exec basename {} \; | cut -d \. -f 1 > ~/Desktop/MyAppList`date +%s.txt`

IsraelTorres · 2010-06-16 15:14:32 5
Remove all the files except abc in the directory
This is sample output - yours may be different.
0

find * ! -name abc -type f -delete

lionping · 2010-07-18 20:25:46 4
find rcs locked file in a given folder

find the files locked by rcs utility Show Sample Output
This is sample output - yours may be different.
```
/etc/RCS/fstab,v
```
0

find /path/to/folder/ -mindepth 1 -maxdepth 2 -name "*,v" -exec sudo rlog -L -R {} \;

bouktin · 2011-01-13 16:07:42 4
Get the dir listing of an executable without knowing its location

whereis (1) - locate the binary, source, and manual page files for a command Not actually better, just expanded a bit. The "whereis" command has the following output: whereis gcc gcc: /usr/bin/gcc /usr/lib/gcc /usr/bin/X11/gcc /usr/share/man/man1/gcc.1.gz therefore the 'ls' error on first line, which could be eliminated with a little extra work. Show Sample Output
This is sample output - yours may be different.
```
ls: cannot access gcc:: No such file or directory
lrwxrwxrwx 1 root root    7 2011-03-03 00:31 /usr/bin/gcc -> gcc-4.5
lrwxrwxrwx 1 root root    7 2011-03-03 00:31 /usr/bin/X11/gcc -> gcc-4.5
lrwxrwxrwx 1 root root   12 2011-03-03 00:31 /usr/share/man/man1/gcc.1.gz -> gcc-4.5.1.gz

/usr/lib/gcc:
total 4
drwxr-xr-x 3 root root 4096 2011-02-14 18:01 i586-suse-linux
```
0

ls -l `whereis gcc`

knathan54 · 2011-11-15 19:45:08 4
what model of computer I'm using?
This is sample output - yours may be different.
0

sudo dmidecode -s system-product-name

jlaunay · 2012-02-08 11:28:46 3
Easy way to display yum repo priorities

This probably only works without modifications in RHEL/CentOS/Fedora. Show Sample Output
This is sample output - yours may be different.
```
priority = 1 [asl-3.0]
priority = 1 [asl-3.0-testing]
priority = 1 [base]
priority = 1 [virtualmin]
priority = 1 [virtualmin-universal]
priority = 50 [epel]
```
0

sed -n -e "/^\[/h; /priority *=/{ G; s/\n/ /; s/ity=/ity = /; p }" /etc/yum.repos.d/*.repo | sort -k3n

eddieb · 2012-09-06 00:09:09 5
Open/Close your co-worker's cd player

Ssh to your co-worker's box and watch them go crazy when the cd player ejects Show Sample Output
This is sample output - yours may be different.
```
<No output>
```
0

while true; do eject && sleep `expr $RANDOM % 5` && eject -t; done;

joeheyming · 2013-01-10 18:40:50 4
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Random Futurama quote

Random Futurama quote from http://cubemonkey.net/quotes/. Change the quote= to change the quote source.

Quick network status of machine

credit to tumblr engineering blog @ http://engineering.tumblr.com/

Find files of two different extensions and copy them to a directory

list files in mtime order

Simple but useful; list files in the current directory in mtime order. Useful if you've been working on something and then take a day or two off.

Emulating netcat -e (netcat-traditional or netcat-openbsd) with the gnu-netcat

Then just nc servername 2600 and ./script.sh kill the client with ctrl+c. You can reconnect several times. kill the server with exit

iso to USB with dd and show progress status

need package: pv apt-get install pv get the iso size in byte with ls -l install-cd.iso /dev/sdb is your USB Device (without partitionNr.)

Add a function you've defined to .bashrc

Example: To store the function addfunction after you have defined it: $ addfunction addfunction

Display a block of text: multi-line grep with perl

-n reads input, line by line, in a loop sending to $_ Equivalent to while () { mycode } -e execute the following quoted string (i.e. do the following on the same line as the perl command) the elipses .. operator behaves like a range, remembering the state from line to line.

get the full description of a randomly selected package from the list of installed packages on a debian system

I put this command on my ~/.bashrc in order to learn something new about installed packages on my Debian/Ubuntu system each time I open a new terminal

Use last argument of last command

Bash shortcut to work with the last argument of your last command

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