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 1
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 [email protected] 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 [email protected]?:'; 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 1
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 3
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 3
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 7

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ubuntu tasksel

The command tasksel allows the choice of packages from the command line to get predefined configurations for specific services (usually this option is offered during installation).

Find the package that installed a command

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)

Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

Find out how old a web page is

I used to use the Firefox "View page info" feature a lot to determine how stale the web page I was looking at was. Now that I use mostly Chrome I miss that feature, so here is a command line alternative using wget. The -S says to display the server response, the --spider says to not download any files/pages, just fetch the header. The output goes to stderr, so to grep it you use 2>&1 to combine the stderr stream with stdout, the pipe that to grep for Last-Modified. You can use curl instead if you have it installed, like this: $ curl --head -s http://osswin.sourceforge.net | grep Mod

Base conversions with bc

Easily convert numbers to their representations in different bases. Passing "ibase=16; obase=8; F2A" to bc will convert F2A (3882 in decimal) from Hex to Octal, and so on.

Send multiple attachments using mailx

If you're users have ever asked your script to email their reports in separate attachments instead of tar'ring them into one file, then you can use this. You'll need the mailx package of course. In Unix you'd want to add an additional parameter "-m" (uuencode foo.txt foo.txt; uuencode /etc/passwd passwd.txt)|mailx -m -s "Hooosa!" [email protected]

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"

Print the IPv4 address of a given interface

Print diagram of user/groups

Parses /etc/group to "dot" format and pases it to "display" (imagemagick) to show a usefull diagram of users and groups (don't show empty groups).

Find the package that installed a command

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Commands by alf (5)

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