Process Types [ fg / bg ] + Signals - Solaris

PROCESS TYPES

FOREGROUND (FG)  / BACKBROUND (BG)

-      bg is used in mount option in /etc/vfstab to mount remote shared mounts in background, if it unmounted / mountd is not working

-      fg mount is default

Let’s have some example …

root@sol-test-2:>/# find ./ -name core &

[1] 27816

root@sol-test-2:>/# find ./ -name statsrep &

[2] 27817

root@sol-test-2:>/# find ./ -name nautilus &

[3] 27818

OK… I initiated 3 processes and send them  in background

root@sol-test-2:>/# jobs

[4]-  Stopped                 prstat -c -n4 2 100

[5]+  Stopped                 prstat -c -n4 2 100

[6]   Running                 find ./ -name core &

[7]   Running                 find ./ -name statsrep &

[8]   Running                 find ./ -name nautilus &

Here all 3 are running in background with their job id i.e. [6] [7] [8]

root@sol-test-2:>/# fg %8

find ./ -name nautilus

./hgfs/VM_SHARE/x86/nmap-6.40/nmap-6.40/zenmap/radialnet/core

^Z

[8]+  Stopped                 find ./ -name nautilus

Now I tried to move the job id 8 in foreground, well it came but now I don’t want it so I did crl+z (suspend)

We can see the same in o/p that job id 8 is stopped

root@sol-test-2:>/# jobs

[4]   Stopped                 prstat -c -n4 2 100

[5]-  Stopped                 prstat -c -n4 2 100

[6]   Running                 find ./ -name core &

[7]   Running                 find ./ -name statsrep &

[8]+  Stopped                 find ./ -name nautilus

root@sol-test-2:>/# ./hgfs/VM_SHARE/x86/nmap-6.40/nmap-6.40/zenmap/radialnet/core

[6]   Exit 1                  find ./ -name core

Again ctrl+c

root@sol-test-2:>/# jobs

[4]   Stopped                 prstat -c -n4 2 100

[5]-  Stopped                 prstat -c -n4 2 100

[8]+  Stopped                 find ./ -name nautilus

root@sol-test-2:>/# bg %8

[8]+ find ./ -name nautilus &

root@sol-test-2:>/# ./usr/include/nautilus

./etc/gconf/gconf.xml.defaults/schemas/apps/nautilus

./etc/gconf/gconf.xml.defaults/apps/nautilus

find: stat() error ./proc/27847/fd/54: No such file or directory

find: stat() error ./proc/27847/fd/55: No such file or directory

find: stat() error ./proc/27847/fd/59: No such file or directory

./.gconf/apps/nautilus

Due to ctrl+z the job id 8 was stopped , now I want it to run again

root@sol-test-2:>/# jobs

[4]-  Stopped                 prstat -c -n4 2 100

[5]+  Stopped                 prstat -c -n4 2 100

[8]   Running                 find ./ -name nautilus &

Now it is running

root@sol-test-2:>/# kill %8

Now I don’t want this process anymore

root@sol-test-2:>/# jobs

[4]-  Stopped                 prstat -c -n4 2 100

[5]+  Stopped                 prstat -c -n4 2 100

[8]   Terminated              find ./ -name nautilus

                                               

SIGNALS

OK… have seen several action movies…

In those movies some Police man’s follow Police manual and some are deadly Police Man’s

“ no FIR no ARREST… execution on the SPOT “

I am just telling these to understand between 2 kill signals

Kill -9 <pid>

Kill -15 <pid>

Kill -9            is the deadly police man… just take the gun and fire from point blank range

Kill -15          is very gentle, following police manual… that first warn the criminal, then chase the criminal if he starts running, then do a fire in air and finally if required shoot him under his knees ( and u know…usually criminals never gives a shit about these type of police man’s)    

                    So the processes treat this signal in same way… this is default

                   If we fire

                   Kill <pid> 

means we are sending SIG-TERM 15 to the Process, that hey Process Bro..

plz shut your self … and the process replies go to hell…

          I think u understand the difference very well between these two.

          There are total 45 signals (1-45)

          Some commonly used are,

          Kill -2 <pid>    [SIGINIT = interrupts the process, ctrl+c]

          Kill -24 <pid>   [SIG-STOP = stop/suspend requested by user, ctrl+z]