D281 Linux Foundation Summary - notes of the linux keys and
commands. NOTES TO DO WELL ON EXAM NEW UPDATE 2025
DOCUMENT Western Governors University
General notes
Files stored - meaning
/etc/passwd file – Where user account information stored.
Primary group membership info stored
Accessible by a user
/etc/group = where supplemental group memberships are
/etc/shadow file – Where user password data stored.
accessible only by root user
/var/log/wtmp = file keeps a log of all users who have logged in and out of the system.
/etc/sysctl.conf = file where there are permanent entries.
,/etc/hosts = contains table of hostnames to IP addresses. Can supplement DNS server.
/etc/resolv.conf = file where address of the DNS server is stored.
/etc = directory contains the account data of users and groups
- Contains configuration files for packages
sbin = directories used only by the root user
/usr/share/doc = directory where additional software packages found.
/dev = directory where hard disk filenames(device files) are stored.
var/log = where files are logged in the directory tree. Maybe using daemons?
/var/log/dmesg = file contains kernal messages during system startup.
, Commands
Viewing process:
ps = command to view processes. Only shows current shell.
ps aux = view all process on the system
ps -ef = view all process on the system.
top = command that regularly updates the output of the process.
- Displays how memory is being used (like free command)
uptime = direct addressing = /proc/loadavg
- How busy the system has been during the last 1, 5, 15
minutes dmesg = to show the kernal log messages
Logging files / viewing them:
syslogd & klogd = logging files. Two daemons. OLD WAY.
rsyslogd = combines those two ^^ functions into ONE
journald = the logging daemon.
journalct1 = command to VIEW jounrald command
last = command that reads the /var/log/wtmp.
- Shows all the users logged in and out of system.
- Displays the reboots records.
- Shows date and time the users were logged in of system.
Networking:
ifconfig = used to display networking configuration info.
- Displays IP address
- Limiting to only modifying network parameters.
ip =replacement for ifconfig. Can do more features.
- ip route------> just the ‘route’ command is becoming outdated.
- ip route show
netstat = provides a large amount of network info. MOST MODERN
- Can display info about network connections
commands. NOTES TO DO WELL ON EXAM NEW UPDATE 2025
DOCUMENT Western Governors University
General notes
Files stored - meaning
/etc/passwd file – Where user account information stored.
Primary group membership info stored
Accessible by a user
/etc/group = where supplemental group memberships are
/etc/shadow file – Where user password data stored.
accessible only by root user
/var/log/wtmp = file keeps a log of all users who have logged in and out of the system.
/etc/sysctl.conf = file where there are permanent entries.
,/etc/hosts = contains table of hostnames to IP addresses. Can supplement DNS server.
/etc/resolv.conf = file where address of the DNS server is stored.
/etc = directory contains the account data of users and groups
- Contains configuration files for packages
sbin = directories used only by the root user
/usr/share/doc = directory where additional software packages found.
/dev = directory where hard disk filenames(device files) are stored.
var/log = where files are logged in the directory tree. Maybe using daemons?
/var/log/dmesg = file contains kernal messages during system startup.
, Commands
Viewing process:
ps = command to view processes. Only shows current shell.
ps aux = view all process on the system
ps -ef = view all process on the system.
top = command that regularly updates the output of the process.
- Displays how memory is being used (like free command)
uptime = direct addressing = /proc/loadavg
- How busy the system has been during the last 1, 5, 15
minutes dmesg = to show the kernal log messages
Logging files / viewing them:
syslogd & klogd = logging files. Two daemons. OLD WAY.
rsyslogd = combines those two ^^ functions into ONE
journald = the logging daemon.
journalct1 = command to VIEW jounrald command
last = command that reads the /var/log/wtmp.
- Shows all the users logged in and out of system.
- Displays the reboots records.
- Shows date and time the users were logged in of system.
Networking:
ifconfig = used to display networking configuration info.
- Displays IP address
- Limiting to only modifying network parameters.
ip =replacement for ifconfig. Can do more features.
- ip route------> just the ‘route’ command is becoming outdated.
- ip route show
netstat = provides a large amount of network info. MOST MODERN
- Can display info about network connections
