locale
man
[section] topic q
as quit)ls
, cd
, cp
, mv
, mkdir
ps
, ^z, jobs
, fg
, bg
, &, echo $?
gcc -Wall source_file.c -o executable_file
./executable_file
echo $?
man 3 sleep
man 2 time
man 3 srand
man 3 rand
stop
message represent?