9 Services Flashcards

Question

when is chrony better than ntpd

Answer 1

when Linux deployments lack constant or consistent network connections, time cant be accurately or immediately synchronized time settings.

Answer 2

Uses port 123/udp edit chrony configuration file /etc/chrony.conf view detail configs, status, and sync info with: chronyc -n tracking chronyc activity

Answer 3

primary Linux schedular is cron. the tool references a crontab file to determine if a task has been assigned. cron jobs can be used to specify tasks each min, hr, day, month, week day.

Answer 4

" * * * * * " * min (0 - 59) * hour (0 - 23) * day of month (1 - 31) * month (1 - 12) *day of week (0 - 6)

Answer 5

system wide crontab file

Answer 6

a per-use crontab

Answer 7

like visudo - its the formal way to edit the cron daemon. cron configurations rely on crontab file Editing the file is used to schedule events

Answer 8

runs a task once at the specified time. flexible as it can be specify a date and time or to run after a given time period. used in an interactive manner where " at {time} " once executed with pop and interactive menu to specify task. - Ctrl + D exits can be used noninteractively by piping "at {time}" ex: echo "Hi" | at 3 pm time arguments excepts: -noon -12:00 p.m. -teatime - 4:00 p.m. -midnight - 12:00 a.m. -now + # {minutes | hour} - time # {min | hr} from now

Answer 9

cron scheduling executes at every occurrence of date/time . at only executes task once and must be made against with the same command to execute similar task

Answer 10

systemd .timer files from unit files: /etc/systemd/system

Answer 11

1. edit /etc/httpd/conf/httpd.conf file. -find Listen and add next to it {localhost | 127.0.0.1}:80 ex: Listen localhost:80 -find DocumentRoot and add "/var/www/html" next to it like Listen ex: DocumentRoot "/var/www/html" indicates to listens for connections to itself over port 80 and where the file that make up the website are found 2. configure firewall to permit inbound http connections (80/tcp) firewall-cmd --permanent --zone=public --add-service=http ^(all one line) firewall-cmd --reload 3. use a text editor to create a simple test web page and save as index.html note: rename old index file 4. change ownership and grp of the file to Apache chown apache:apache /var/www/html/index.html 5. enable and start/restart service systemctl enable httpd systemctl {start | restart} httpd 6. launch browser to display webpage firefox http://localhost

Answer 12

1. deploy NFS server and install, enable, and start service. systemctl enable nfs-server systemctl start nfs-server 2. create or select directories on file server that should be shared/exported over network. note these and possible required permissions 3. Edit /etc/exports file to make these resources available over network -must use absolute path ex: {(dir | file) path} {Network ID/CIDR} ({privileges - symbolic}, sync) the dir/file will be available to clients connecting from that subnet and have specified privileges {(dir | file) path} *(ro, sync) the dir/file can be accessible from any client IP, the "ro" permission specifies read-only (optional) 4. restart service 5. might need to configure firewalls for NFS connections: 111/tcp (and udp) plus 2049/tcp (and /udp)

Answer 13

1. display available directories on remote file server showmount -e {remote -server-IP-address} 2. on client, mount exported dir to a local mount point can create subdir int /mnt for nfs-share mount -t nfs4 {remote-server-IP}:{NFS dir | file} {mount-point} can mount -t samba2 work?

Answer 14

print management system for Linux enable a computer to be a print server. CUPS host can initiate client print jobs. it can process different data formats on the same server.

Answer 15

provides a web-based interface for configuring the service .

Answer 16

CUPS configuration files that the provided CUPS web-based interface modifies

Answer 17

1. install service and start systemctl enable cups system start cups 2. open fire wall to CUPS port 631/tcp 3. management interface is access from web: http://localhost:631

Answer 18

submits files via the command line for printing, and are sent to a default printer unless specified a printer to print or queue.

Answer 19

-E - force encryption -P {destination} - specify printer -# {copies} - copies 1-100 -T {name} - set job name -o {option} set job option like landscape mode, scale output, double-sided etc. -p print specified files with shaded header including date, time, job name, page # -r printed files should be deleted after printing

Answer 20

display existing print jobs a printer is managing

Answer 21

print date in specified format formation date is an argument with with preceding "+" ex: date +[argument] - %A - Display the full weekday name. -%B - Display the full month name. -%F - Display the date in YYYY-MM-DD format. -%H - Display the hour in 24-hour format. -%I - Display the hour in 12-hour format. -%j - Display the day of the year. -%S - Display seconds. -%V - Display the week of the year. -%x - Display the date representation based on the locale. -%X - Display the time representation based on the locale. -%Y - Display the year.

Answer 22

maintains date of system format: <24 hour time ##:##:##>

Answer 23

set system date and time info subcommand: status - show current settings restart - sync local (system) clock base on hardware list-timezones set-timezones {time-zone} ex: timedatectl set-timezone "America/Denver" set-time {HH:MM:SS} options: -H execute on remote host specified by IP or hostname --no-ask-password prevent user being asked to authenticate when performing a priv task --adjust-system-clock sync system clock to real-time clock -M {local container} execute on local container

Answer 24

store regional time zones and can use to trouble shoot. they are special files and to change time zone, create a sym link to on of the time zones in /etc/localtime file