Process ID using ps aux

Question

I'm a newbie to shell programming. Assuming that I've started a program(eg NetBeans) from my terminal, if I type

ps aux|grep netbeans

I get the the output

pre      18775  1.2  0.0  12524  1972 pts/3    S    20:17   0:00 

where 18775 specifies the PID etc of the process.

Then I kill it using

kill 18775.

upon which the NetBeans UI disappears. If I try to get the pid by using the first command, I still get:

pre      19137  0.0  0.0   9136  1068 pts/3    S+   20:19   0:00 grep --color=auto netbeans

If the process has been killed, why does it still show the above output?

Answer 1

grep is grepping itself. Try something like:

ps aux |grep [n]etbeans

this keeps grep from showing itself in the output

Answer 2

Never use ps together with grep.

Rather, use killall netbeans, pkill netbeans to kill it. For the process ID pgrep netbeans.

More on ps and grep.

Answer 3

Because that's the PID for the grep process which is queued up to run after ps aux.