Commands by alf

Commands by alf (5)

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Untar a directory in a tar file over ssh

This may be listed already but this command is useful to untar a specific directory to a different server.
This is sample output - yours may be different.
0

cat tarfile.tar.gz | ssh server.com " cd /tmp; tar xvzf - directory/i/want"

alf · 2011-02-11 17:10:01 4
Automatd ssh public key setup without ssh-copy-id

Some servers don't have ssh-copy-id, this works in those cases. It will ask for the destination server, this can be IP, hostname, or user@hostname if different from current user. Ssh keygen will let you know if a pubkey already exists on your system and you can opt to not overwrite it.
This is sample output - yours may be different.
-2

echo 'Host or User@Host?:'; read newserver && ssh-keygen -N "" -t rsa -f ~/.ssh/id_rsa ; ssh $newserver cat <~/.ssh/id_rsa.pub ">>" ~/.ssh/authorized_keys ; ssh $newserver

alf · 2010-05-07 06:24:53 5
Show interface/ip using awk

Interfaces like lo can be omitted from the beginning, there are probably better ways of doing this, i'm a noob at awk. Show Sample Output
This is sample output - yours may be different.
```
lo 127.0.0.1
wlan0 192.168.1.100
```
5

ifconfig -a| awk '/^wlan|^eth|^lo/ {;a=$1;FS=":"; nextline=NR+1; next}{ if (NR==nextline) { split($2,b," ")}{ if ($2 ~ /[0-9]\./) {print a,b[1]}; FS=" "}}'

alf · 2010-04-15 04:34:28 19
Update zone file Serial numbers

Will edit *.db files in the same directory with todays date. Useful for doing a mass update to domains on a nameserver, adding spf records, etc. Looks for a string starting with 200 or 201 followed by 7 numbers, and replaces with todays date. This won't overwrite Ip's but i would still do some double checking after running this. Make sure your server's date is correct, otherwise insert your own serial number. rndc reload should usually follow this command.
This is sample output - yours may be different.
7

sed -i 's/20[0-1][0-9]\{7\}/'`date +%Y%m%d%I`'/g' *.db

alf · 2010-03-24 07:28:58 11
Use ping to test if a server is up

Bash scrip to test if a server is up, you can use this before wget'ing a file to make sure a blank one isn't downloaded.
This is sample output - yours may be different.
-1

if [ "$(ping -q -c1 google.com)" ];then wget -mnd -q http://www.google.com/intl/en_ALL/images/logo.gif ;fi

alf · 2010-03-23 04:15:03 11

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Clone IDE Hard Disk

This command clone the first partition of the primary master IDE drive to the second partition of the primary slave IDE drive (!!! back up all data before trying anything like this !!!)

floating point operations in shell scripts

using bc is for sissies. dc is much better :-D Polish notation will rule the world...

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" }

Advanced python tracing

Trace python statement execution and syscalls invoked during that simultaneously

analyze traffic remotely over ssh w/ wireshark

This captures traffic on a remote machine with tshark, sends the raw pcap data over the ssh link, and displays it in wireshark. Hitting ctrl+C will stop the capture and unfortunately close your wireshark window. This can be worked-around by passing -c # to tshark to only capture a certain # of packets, or redirecting the data through a named pipe rather than piping directly from ssh to wireshark. I recommend filtering as much as you can in the tshark command to conserve bandwidth. tshark can be replaced with tcpdump thusly: $ ssh root@example.com tcpdump -w - 'port !22' | wireshark -k -i -

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"

SSH Auto-login with password

You need to install "sshpass" for this to work. apt-get install sshpass

Prints line numbers

If you don't have nl on your system, this achieves a similar effect, the default behavior in nl is to not number blank lines, but this does.

Command to logout all the users in one command

Get the total length of time in hours:minutes:seconds (HH:MM:SS) of all video (or audio) in the current dir (and below)

change the *.avi to whatever you want to match, you can remove it altogether if you want to check all files.

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Commands by alf (5)

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