6

shell
; && ||
echo "" > /root/tmp.txt
echo "" > /root/tmp.txt && echo "went ok"
echo "" > /root/tmp.txt ; echo "went ok"
echo "" > /root/tmp.txt || echo "failed"

processes.

foreground - controlled through a terminal session.
background - process that not connected to a terminal.
 -- daemon - special type of the background process that starts at system startup and runs forever - they don't die. (services).
ps -aef aux
pidof
PID, PPID, UID, GID
in shell
echo $$
echo $PPID
effective process id - passwd program example.
chown and chmod - how to get root shell.
process states:
* running
* waiting
* stopped
* zombie

init, process ID 1

fork()
system()
exec()

parent processes, child processes.

in Linux, orphaned process gets adopted by the init.

Stack, Heap, Data, Text.


nohup
&

$ atril
$ atril &
$ jobs
$ nohup atril
screen

ctrl-z
ctrl-c
fg
bg
vim test.c
cc -o test test.c

echo $?
return 0;

process environment, or environment variables.

processes
ps
pstree
wait, kill
signals

nice expensiveprocess

at 10:05
echo "aaa" > /tmp/aaa
^d

watch ls /tmp/

init process