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Exam Study Topics - Coggle Diagram
Exam Study Topics
Signals
kill() signal with negative vs. positive pid.
positive id - pid of process
0 - sent to every process in the process group of the calling process
-1 - every process for which the calling process has permission to send signals, except for process 1 (init).
These
SIGCHLD
child stopped or terminated
SIGINT
interrupt from keyboard
SIGTSTP
stop typed at terminal
SIGCONT
continue if stopped
SIGTERM
termination signal
SIGKILL
kill signal
These
SIG_DFL
use default behavior for signals
SIG_IGN
ignore signals
How to get environmental variable from inside C
getenv()
File Descriptors
fileno()
returns file descriptor associated with a stream
Processes
retrieving status from exited child processes with macros
WIFEXITED
returns true if the child terminated normally, so like calling exit(3) or exit(2) or return from main
WIFSTOPPED
WIFSIGNALED