xsos – a tool for sysadmins and support

Here is a very nice article that you may find useful


change the output format for time command

If you are doing some scripting and using ‘time’ command, then you know sometimes it becomes difficult to capture the output as the output would be something like this:

: amit ; time ls

real    0m0.002s
user    0m0.000s
sys 0m0.001s

So, it is better to change that format. Here is simple example:

TIMEFORMAT=’real %3R user %3U sys %3S pcpu %P’ time ls
amit ;  TIMEFORMAT=’real %3R user %3U sys %3S pcpu %P’ time ls
0.00user 0.00system 0:00.00elapsed 0%CPU (0text+0data 2432max)
0inputs+0outputs (0major+109minor)pagefaults 0swaps
amit ; TIMEFORMAT=’real %3R user %3U sys %3S’
amit ; time ls
real 0.001 user 0.001 sys 0.000
amit ;
amit ; TIMEFORMAT=’TIMEOUTPUT = real %3R user %3U sys %3S’
amit ; time ls
TIMEOUTPUT = real 0.001 user 0.001 sys 0.000
amit ;

Generate random string for various use case

Some times I need random string, for example to use as email seperator or to use in some API. One way is to use tools like /dev/[u]random or od and other such. But they seem cubersome after I figured this out.

openssl rand <length>
openssl rand 10

This alone without some parameters is not interesting thoug. You can use ‘-base64’ or ‘-hex’ to select the encoding.

So if you execute the above you will get something like this

$ openssl rand -hex 10

$ openssl rand -base64 10