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Copy via tar pipe while preserving file permissions (cp does not!; run this command with root!)

cp options: -p will preserve the file mode, ownership, and timestamps -r will copy files recursively also, if you want to keep symlinks in addition to the above: use the -a/--archive option
This is sample output - yours may be different.
4

cp -pr olddirectory newdirectory

stanishjohnd · 2009-08-22 22:11:24 8
Download Youtube Playlist

This will download a Youtube playlist and mostly anything http://code.google.com/apis/youtube/2.0/reference.html#Video_Feeds The files will be saved by $id.flv
This is sample output - yours may be different.
3

y=http://www.youtube.com;for i in $(curl -s $f|grep -o "url='$y/watch?v=[^']*'");do d=$(echo $i|sed "s|url\='$y/watch?v=$.*$&.*'|\1|");wget -O $d.flv "$y/get_video.php?video_id=$d&t=$(curl -s "$y/watch?v=$d"|sed -n 's/.* "t": "$[^"]*$",.*/\1/p')";done

matthewbauer · 2009-08-22 21:31:29 53
YES = NO
This is sample output - yours may be different.
4

yes n

elzapp · 2009-08-22 20:32:23 116
Copy via tar pipe while preserving file permissions (run this command as root!)

It's the same like 'cp -p' if available. It's faster over networks than scp. If you have to copy gigs of data you could also use netcat and the tar -z option in conjunction -- on the receiving end do: # nc -l 7000 | tar -xzvpf - ...and on the sending end do: # tar -czf - * | nc otherhost 7000
This is sample output - yours may be different.
1

tar -C /oldirectory -cvpf - . | tar -C /newdirector -xvf -

Cowboy · 2009-08-22 20:05:49 5
Print a random 8 digit number
This is sample output - yours may be different.
5

jot -r -n 8 0 9 | rs -g 0

curiousstranger · 2009-08-22 19:31:17 6
watch iptables counters

This will allow you to watch as matches occur in real-time. To filter out only ACCEPT, DROP, LOG..etc, then run the following command: watch 'iptables -nvL | grep -v "0 0" && grep "ACCEPT"' The -v is used to do an inverted filter. ie. NOT "0 0"
This is sample output - yours may be different.
7

watch --interval 0 'iptables -nvL | grep -v "0 0"'

Code_Bleu · 2009-08-22 18:18:05 51
Verbosely delete files matching specific name pattern, older than 15 days.
This is sample output - yours may be different.
6

find /backup/directory -name "FILENAME_*" -mtime +15 | xargs rm -vf

monkeymac · 2009-08-22 16:58:23 6
Remove empty directories

It only works in zsh
This is sample output - yours may be different.
1

rmdir **/*(/^F)

unixmonkey5248 · 2009-08-22 12:31:55 3
Cleanup firefox's database.

Sqlite database keeps collecting cruft as time passes, which can be cleaned by the 'vacuum;' command. This command cleans up the cruft in all sqlite files relating to the user you have logged in as. This command has to be run when firefox is not running, or it will exit displaying the pid of the firefox running.
This is sample output - yours may be different.
11

pgrep -u `id -u` firefox-bin || find ~/.mozilla/firefox -name '*.sqlite'|(while read -e f; do echo 'vacuum;'|sqlite3 "$f" ; done)

kamathln · 2009-08-22 10:36:05 10
List files and sizes

List files and sizes
This is sample output - yours may be different.
0

find / -type f -exec wc -c {} \; | sort -nr | head -100

hemanth · 2009-08-22 09:38:44 10
Reverse DNS lookups

Reverse DNS lookups, from a file with list of IP's, here the file is called lookups.txt
This is sample output - yours may be different.
-1

sed 's/$[0-9]*$\.$[0-9]*$\.$[0-9]*$\.$[0-9]*$.in-addr.arpa domain name pointer$.*$\./\4.\3.\2.\1\5/' \ lookups.txt

hemanth · 2009-08-22 09:37:20 4
Ping sweep without NMAP

Ping sweep without NMAP
This is sample output - yours may be different.
3

for i in `seq 1 255`; do ping -c 1 10.10.10.$i | tr \\n ' ' | awk '/1 received/ {print $2}'; done

hemanth · 2009-08-22 09:34:27 12
DNS cache snooping

DNS cache snooping
This is sample output - yours may be different.
0

for i in `cat names.txt`; do host -r $i [nameserver]; done

hemanth · 2009-08-22 09:26:31 3

Show account security settings Show Sample Output

chage -l <user>

hemanth · 2009-08-22 09:12:03 6

List all groups and the user names that were in each group

"cut" the user names from /etc/passwd and then running a loop over them. Show Sample Output
This is sample output - yours may be different.
```
avahi-autoipd:avahi-autoipd
avahi:avahi
backup:backup
bin:bin
daemon:daemon
debian-tor:debian-tor
debian-transmission:debian-transmission
games:games
gdm:gdm
gnats:gnats
haldaemon:haldaemon
```
3

for u in `cut -f1 -d: /etc/passwd`; do echo -n $u:; groups $u; done | sort

hemanth · 2009-08-22 09:06:02 7
Remove empty directories

You can also use, $ find . -depth -type d -exec rmdir {} \; 2>/dev/null
This is sample output - yours may be different.
6

find . -type d -empty -delete

hemanth · 2009-08-22 09:03:14 8
Random number generation within a range N, here N=10
This is sample output - yours may be different.
3

echo $(( $RANDOM % 10 + 1 ))

hemanth · 2009-08-22 08:57:01 5
power off system in X hours form the current time, here X=2
This is sample output - yours may be different.
1

echo init 0 | at now + 2 hours

hemanth · 2009-08-22 08:10:46 3
Day Date Time> Instead of $ or # at the terminal
This is sample output - yours may be different.
-1

export PS1='\D{%a %D %T}> '

hemanth · 2009-08-22 08:07:47 4
check open ports

Tested in Linux and OSX Show Sample Output
This is sample output - yours may be different.
```
kopete  1782   user   18u  IPv4  12568      0t0  TCP *:8010 (LISTEN)
sshd    2215   root    3u  IPv4  35583      0t0  TCP *:22 (LISTEN)
```
19

lsof -Pni4 | grep LISTEN

evenme · 2009-08-21 22:51:41 71
purge old stale messages on a qmail queue
This is sample output - yours may be different.
0

for i in `grep "unable to stat" /var/log/syslog | cut -d "/" -f 3 | sort | uniq`; do find /var/qmail/queue -name $i -type f -exec rm -v {} \; ; done

foob4r · 2009-08-21 22:03:39 3
delete all DrWeb status, failure and other messages on a postfix server
This is sample output - yours may be different.
0

mailq | grep DrWEB | awk {'print $1'} | sed s/*//g | postsuper -d -

foob4r · 2009-08-21 22:01:41 3
less an message on a postfix mailsystem with a specific message-id
This is sample output - yours may be different.
0

id=<XXXX>; find /var/spool/postfix/ -name $id -exec less {} \;

foob4r · 2009-08-21 21:58:58 3
replace old htaccess php AddHandler values with new one

Alter "AddHandler php5-cgi .php" and "AddHandler php4-cgi .php" entries to new "AddHandler x-httpd-php5 .php" respective php4 entries in all .htaccess files under /var/www Show Sample Output
This is sample output - yours may be different.
```
-
```
0

find /var/www/ -type f -name ".htaccess" -exec perl -pi -e 's/AddHandler[\s]*php(4|5)-cgi/AddHandler x-httpd-php\1/' {} \;

foob4r · 2009-08-21 21:55:22 3
floating point operations in shell scripts

allows you to use floating point operations in shell scripts Show Sample Output
This is sample output - yours may be different.
```
.6000
```
3

echo "scale=4; 3 / 5" | bc

foob4r · 2009-08-21 21:51:46 3
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Display calendar with specific national holidays and week numbers

NB when you run this gcal command in your shell, holidays are highlighted but this highlighting does not show in the sample output (above). To find full details on gcal options: gcal --long-help | less Example for United States, Pennsylvania: gcal -K -q US_PA 2009 # display holidays in USA/Pennsylvania for 2009 (with week numbers) Example for Hong Kong: gcal -K -q HK 2009 # display holidays in Hong Kong for 2009 (with week numbers)

Find usb device in realtime

Using this command you can track a moment when usb device was attached.

Shell recorder with replay

If you provide the option -t to the script command and redirect stderr into a file, the timing information on what is going on on the terminal, is also stored. You can replay the session via the scriptreplay command, where you can also provide a speedup factor (see the man page for details). Great for demonstration purposes ...

display an embeded help message from bash script header

With this one liner you can easily output a standard help message using the following convention: Usage: is the start marker Stop at the last #

Convert CSV to JSON

Replace 'csv_file.csv' with your filename.

Rename a file with a random name

Give files a random name (don't ask why :-) The function will rename files but maintain their extensions. BUG: If a file doesn't have an extension it will end up with a dot at the end of the name. The parameter '8' for pwgen controls the length of filenames - eight random characters.

Remove audio stream from a media file

This syntax also works for ffmpeg as avconv is a fork of ffmpeg.

Make a server's console beep when the network is down

This is like ping -a, but it does the opposite. It alerts you if the network is down, not up. Note that the beep will be from the speaker on the server, not from your terminal. Once a second, this script checks if the Internet is accessible and beeps if it is not. I define the Net as being "UP", if I can ping Google's public DNS server (8.8.8.8), but of course you could pick a different static IP address. I redirect the beep to /dev/console so that I can run this in the background from /etc/rc.local. Of course, doing that requires that the script is run by a UID or GID that has write permissions to /dev/console (usually only root). Question: I am not sure if the -W1 flag works under BSD. I have only tested this under GNU/Linux using ping from iputils. If anybody knows how portable -W is, please post a comment.

Advanced python tracing

Trace python statement execution and syscalls invoked during that simultaneously

Look up the definition of a word

A bash function might also be useful: $ dict() { curl dict://dict.org/d:$1; } Or if you want less verbose output: $ dict() { curl -s dict://dict.org/d:$1 | perl -ne 's/\r//; last if /^\.$/; print if /^151/../^250/'; }

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