RHCSA Exam | Questions And Answers Latest {2024- 2025} A+ Graded | 100% Verified
Repeat last command - !!
Repeat last argument in current command - !$
Kernel log message command - dmesg
File usage - du -hsx
h - human, s - summarize,
x - single fs
Umount a busy drive - kill -9 'lsof +D /mnt/cdrom'
(list open files, +D=directory and contents)
Compare file contents - diff
Search for all gzip files, not dirs - find -type f -name *.gz
Command to tell crond what to do - crontab
crontab order - Min, hour, date, month, day, command
Show what's in crond - crontab -l
Turn on firewall for run levels 2-5 - chkconfig iptables on
Check if <cmd> is running - service <cmd> status <=old
,systemctl status <cmd> <=new
Set tasks for crond - crontab -e
e = edit
Mail location - /var/spool/mail
Command to check messages - mail
Check <cmd> run level schedule - chkconfig --list <cmd>
Print a file's number of lines - wc -I <file>
l=line
User account commands - useradd, userdel, usermod
usermod switches - G second group, g main group, u user ID num, d home, s shell
Set user password - passwd --stdin <user>
Delete user account AND home dir - userdel -r
r = remove
Force user password change - chage -d 0 <user>
change + age
-d = last day
Group-file field categories - /etc/group gname:x:gid:users
,User account lock cmd - usermod -L or -U <usr>
U = unlock
Check if user account is locked - less /etc/passwd
user:! means locked
:!! means no password set
Show password parameters - chage -l <login>
l = list
Set password max life - chage -M <# of days>
Firewall settings GUI - system-config-firewall
Scan for open ports - netstat -tulpn (as root)
nmap 192.168.1.10
tu=tcp/udp, l=only listening, p=sh pid, n=numeric address
Yum repo location - /etc/yum.repos.d
Turn <cmd> on for important run levels - chkconfig <cmd> on
cmd to see if crond is running - ps -ef | grep crond
e=every process, f=ASCII process hierarchy
or
service crond status <=old
systemctl status crond <=new
start crond - service crond start <=old
, systemctl start crond <=new
turn <cmd> on for important run levels - chkconfig <cmd> on
check what levels <cmd> is set to run at - chkconfig --list <cmd>
cmd to set instructions for crond - crontab -e
script comment symbol - #
crontab format - min hr date month day command
what day number is Sunday - zero
cmd to get crontab help - man 5 crontab
cmd to view email - mail
where are emails stored - /var/spool/mail
show list of crond tasks - crontab -l
be careful of this when creating crond tasks - the created task will run as the user you are logged in as
cmd for disk usage - du -hsx
h - human, s - summarize, x - single fs
cmd to find all open instances of cdrom - lsof +D /dev/cdrom
list open files, +D is for all instances and included files
Repeat last command - !!
Repeat last argument in current command - !$
Kernel log message command - dmesg
File usage - du -hsx
h - human, s - summarize,
x - single fs
Umount a busy drive - kill -9 'lsof +D /mnt/cdrom'
(list open files, +D=directory and contents)
Compare file contents - diff
Search for all gzip files, not dirs - find -type f -name *.gz
Command to tell crond what to do - crontab
crontab order - Min, hour, date, month, day, command
Show what's in crond - crontab -l
Turn on firewall for run levels 2-5 - chkconfig iptables on
Check if <cmd> is running - service <cmd> status <=old
,systemctl status <cmd> <=new
Set tasks for crond - crontab -e
e = edit
Mail location - /var/spool/mail
Command to check messages - mail
Check <cmd> run level schedule - chkconfig --list <cmd>
Print a file's number of lines - wc -I <file>
l=line
User account commands - useradd, userdel, usermod
usermod switches - G second group, g main group, u user ID num, d home, s shell
Set user password - passwd --stdin <user>
Delete user account AND home dir - userdel -r
r = remove
Force user password change - chage -d 0 <user>
change + age
-d = last day
Group-file field categories - /etc/group gname:x:gid:users
,User account lock cmd - usermod -L or -U <usr>
U = unlock
Check if user account is locked - less /etc/passwd
user:! means locked
:!! means no password set
Show password parameters - chage -l <login>
l = list
Set password max life - chage -M <# of days>
Firewall settings GUI - system-config-firewall
Scan for open ports - netstat -tulpn (as root)
nmap 192.168.1.10
tu=tcp/udp, l=only listening, p=sh pid, n=numeric address
Yum repo location - /etc/yum.repos.d
Turn <cmd> on for important run levels - chkconfig <cmd> on
cmd to see if crond is running - ps -ef | grep crond
e=every process, f=ASCII process hierarchy
or
service crond status <=old
systemctl status crond <=new
start crond - service crond start <=old
, systemctl start crond <=new
turn <cmd> on for important run levels - chkconfig <cmd> on
check what levels <cmd> is set to run at - chkconfig --list <cmd>
cmd to set instructions for crond - crontab -e
script comment symbol - #
crontab format - min hr date month day command
what day number is Sunday - zero
cmd to get crontab help - man 5 crontab
cmd to view email - mail
where are emails stored - /var/spool/mail
show list of crond tasks - crontab -l
be careful of this when creating crond tasks - the created task will run as the user you are logged in as
cmd for disk usage - du -hsx
h - human, s - summarize, x - single fs
cmd to find all open instances of cdrom - lsof +D /dev/cdrom
list open files, +D is for all instances and included files
