Pario TechnoBlob » awk

My 10 most used linux commands

Hans-Henry Jakobsen — Mon, 25 Feb 2008 07:49:40 +0000

This is a oneliner bash command to determine my 10 most used linux commands according to my history file

history | awk '{CMD[$2]++;count++;}END { for (a in CMD)print CMD[a] " " CMD[a]/count*100 "% " a;}' | grep -v "./" | column -c3 -s " " -t | sort -nr | nl |  head -n10

The result

     1  188  37.6%  vi
     2  38   7.6%   ls
     3  24   4.8%   cat
     4  22   4.4%   apt-get
     5  12   2.4%   date
     6  11   2.2%   tail
     7  11   2.2%   cd
     8  10   2%     rm
     9  10   2%     man
    10  9    1.8%   basename

It looks like i use vim a lot on my home server. You should try it yourself and see what commands you use the most.

Source: http://linux.byexamples.com

Apache web connections pr hour

Hans-Henry Jakobsen — Thu, 21 Feb 2008 22:26:15 +0000

This is a bash oneliner to show Apache web connections pr hour. It lists up the IPs that has accessed your webserver and the amount og accesses.

# cat /var/log/apache2/access_log_pario.no | grep "21/Jan/2008:.." | awk {' print $4":"$1 '} | sed 's/\[//g' | awk -F : {' print $1":"$2"\t\t"$5 '} | sort | uniq -c

Example output

37 21/Jan/2008:00          192.168.0.10

This shows that I had 37 hits from 00:00 – 01:00 in 20th February 2008.

Allow NFS through iptables

Hans-Henry Jakobsen — Thu, 20 Dec 2007 09:50:41 +0000

This is one way to determine the ports needed to open in your iptables rules to get NFS to work properly. First we need to determine the ports NFS uses

rpcinfo -p | awk -F " " '{print $3 ", " $4 ", " $5}' | sort | uniq

Notice!
Since portmap assigns ports on random this example is only valid as long as you don’t restart your NFS.

On my system, a RedHat Enterprise Linux WS 4, the result was

proto, port,
tcp, 111, portmapper
tcp, 2049, nfs
tcp, 32771, nlockmgr
tcp, 768, rquotad
tcp, 782, mountd
udp, 111, portmapper
udp, 2049, nfs
udp, 32768, nlockmgr
udp, 765, rquotad
udp, 779, mountd

This gave me a nice overview of protocols (tcp/udp) and ports used.

Now the rules

iptables -A RH-Firewall-1-INPUT -s 192.168.0.0/255.255.255.0 -i eth0 -p tcp -m state --state NEW -m multiport --dports 111,2049,32771,768,782 -j ACCEPT
iptables -A RH-Firewall-1-INPUT -s 192.168.0.0/255.255.255.0 -i eth0 -p udp -m state --state NEW -m multiport --dports 111,2049,32768,765,779 -j ACCEPT

You see that the multiport statement is just like the result of my rpcinfo command above.

Remember to save your new rules, othervise they will disappear the next time the iptables rules are being loaded.

In addition to this rule you should add the iptables rule for ssh access I wrote about earlier.

Another way to determine the ports

nmap -sC -p 111 localhost

Notice!
This solution won’t work after a reboot of the server since NFS changes ports. One way to overcome this problem is to follow the instructions in a newer post I’ve made about RedHat and NFS.

Adjust images to a digital frame (480×234 pixels)

Hans-Henry Jakobsen — Sun, 25 Nov 2007 12:03:38 +0000

This bash script adjusts images to fit in a digital frame with a resolution of 480×234 pixels however by using the size 832×468 pictures are displayed sharper on some frames. Normally, narrower pictures will have black borders at both sides when displayed. but this script makes the border color the average of the picture.

The following linux tools are used in the script: convert and montage, bash, od and awk. od is part of the textutils package in Debian.

#!/bin/bash
# current directory contains source JPG files
# $DESTINATION is where the prepared JPG files are stored
# $TEMP is a temporary directory
TEMP=TEMP
DESTINATION=DESTINATION
GEO=832x468 # geometry of target JPG files and resize value

for FILE in *.JPG
do
convert -resize 1x1 "$FILE" "$TEMP/1x1.bmp"
od -A n -j 54 -t u1 "$TEMP/1x1.bmp" | awk -v f="$FILE" -v des="$DESTINATION/" -v geo="$GEO" '
{
print "montage -geometry", geo, "-resize", geo, "-background rgb\\(" $3 \
"," $2 "," $1 "\\) \"" f "\" \"" des f "\"";
exit;
}'

done | sh -x

Source: comp.graphics.misc

nslookup-scan of IP-range/subnet

Hans-Henry Jakobsen — Tue, 04 Sep 2007 09:57:45 +0000

#!/bin/bash
# nslookup-scan of IP-range

# It's possible to add more networks separated with space
NETS="192.168.0"

IPRange="1 254"
for NET in $NETS; do
  for n in $(seq $IPRange); do
        ADDR=${NET}.${n}
        echo "${ADDR},`nslookup ${ADDR} | awk -F "=" '{ print $2 }'|sed 's/^[ t]*//' | sed '/^$/d' | |sed 's/.$//'`"
  done
done

Result

192.168.0.1,cba.infra.no
192.168.0.2,bca.infra.no
192.168.0.3,abc.infra.no
192.168.0.4,
192.168.0.5,
192.168.0.6,
192.168.0.7,
192.168.0.8,