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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 75
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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Speaking alarm clock

This ran on a ubuntu box using espeak for speaking text with the bash shell. On a mac you should use 'say'. Also you can change your alarm interval and your snooze interval which are currently 8 hours and 1 minute. I would run this via cron yet it's easier to disable if you run it as a command like this :P

Limit the transfer rate of a pipe with pv

-L RATE, --rate-limit RATE Limit the transfer to a maximum of RATE bytes per second. A suffix of "k", "m", "g", or "t" can be added to denote kilobytes (*1024), megabytes, and so on. It must be an integer.

Pick a random line from a file

Produces a list of when your domains expire

Create a text file called domainlist.txt with a domain per line, then run the command above. All registries are a little different, so play around with the command. Should produce a list of domains and their expirations date. I am responsible for my companies domains and have a dozen or so myself, so this is a quick check if I overlooked any.

Unzip multiple files with one command

With this command you can easily unzip multiple zip files with just one command. All you need to do is to use single quotes.

list block devices

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

Print number of mb of free ram

Here we instead show a more real figure for how much free RAM you have when taking into consideration buffers that can be freed if needed. Unix machines leave data in memory but marked it free to overwrite, so using the first line from the "free" command will mostly give you back a reading showing you are almost out of memory, but in fact you are not, as the system can free up memory as soon as it is needed. I just noticed the free command is not on my OpenBSD box.

run shell with your commandlinefu.com's favourites as bash_history

This makes your commandlinefu.com's favorites appear as most recent commands in your history.

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" }

Extract track 9 from a CD

Using mplayer to extract audio file from a CD

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