Accurate calculation of memory utilization in Linux

Hi, We use ps aux | awk '{sum +=$4}; END {print sum}' to find the total memory utilization excluding the buffers and cache. This one manipulates the wrong data at some instances. No idea why  . So in addition to this we can adopt the below commands as wel.. free -m | grep "+" | awk {'print $3/$4*100'} or more handy U=`free -m | grep "+" | awk {'print $3'}`;F=`free -m | grep "+" | awk {'print $4'}`;echo "scale=2;$U/$F*100"| bc There may be another ways as well. Comments please.

Check remote UDP connectivity from Linux

Hi there,
You all know how to check TCP port connectivity from a Linux or UNIX machine to a remote machine using telnet as per th example below
$ telnet 127.0.0.1 25

but we can't adopt TELNET to check UDP connectivity.

Linux and most of the UNIXes come with a network layer utility called nc (abbreviation for netcat) which is very useful to check UDP connectivity and to explore a lot with both TCP and UDP.

An example is shown below

# nc -v -u -z -w 3 172.24.16.131 123
Connection to 172.24.16.131 123 port [udp/ntp] succeeded!