19. The Linux System User commands includes executable programs and scripts The shell interprets user commands. It is responsible for finding the commands and starting their execution. Several different shells are available. Bash is popular, The kernel manages the hardware resources for the rest of the system.
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56. Interpreting File Permissions -rwxrwxrwx Other permissions Group permissions Owner permissions Directory flag (d=directory; l=link)
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73. Processes [root@penguinvm log]# sleep 10h & [1] 6718 [root@penguinvm log]# ps -ef UID PID PPID C STIME TTY TIME CMD root 6718 6692 0 14:49 ttyp0 00:00:00 sleep 10h & causes process to be run in “background” Job Number Process ID (ID) Parent Process ID
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85. Security - Important Files /etc/passwd - password file /etc/shpasswd - shadow password file /etc/group -lists groups and users contained in groups /etc/services - lists network services and their ports /etc/ftpusers - contains list of accounts that cannot use ftp /etc/hosts.equiv - generic list of remote users ~/.rhosts - list of remote users for a specific account /etc/hosts - host definition list /etc/hosts.lpd - hosts who can use remote printing /etc/hosts.allow - lists services that remote users are allowed to use /etc/hosts.deny - lists services tthat remote users are not allowed to use /etc/nologin - no login message that also disables logins /etc/securetty - lists legal terminals for root to login from /etc/exports - lists locations that can be remotely accessed via NFS /etc/syslog.conf - configures the syslog facility /etc/inetd.conf - configures inetd
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89. Linux in the Business World Issues and observations