RHCSA, EX200, Red Hat Certified
Systems Admin
how to redirect errors to a file? - Answer- command 2> <$filename>
2> will over write the file and 2>> will append
how to redirect both standard error and output to a file and have no outputs show on
screen? - Answer- &>
how to redirect standard error into standard output? - Answer- 2 > &1
how to grep opposites? - Answer- grep -v
select all that do not start with l,i,n,u,x - Answer- grep -v '[^linux]'
returns everything not beginning with the letters: l, i, n, u, x
what does ? mean in regex - Answer- character before is optional
what does + mean in regex - Answer- preceding item is matched 1 or more times
what is scp? - Answer- secure copy protocol. do it over ssh. encrypted. old way to
transfer. can send commands to the other server.
what is sftp? - Answer- secure file transfer protocol. or ssh file transfer protocol. can
connect and live inside the other server.
can type get <$filename> to get copy the files back
what is tar -cvf - Answer- create, verbose, use this archive name.
how to see files in archive - Answer- tar -tf
what does tar -xzvf do - Answer- eXtract gZip Verbosely Filename
star command. archive utility. not default. need to yum install. - Answer- big data sets
and files.
what is apropos and mandb - Answer- apropos searches the titles of man pages for
this key.
man page is not indexed and cached so we need to run mandb and it'll be recorded.
how to see all the commands if stuck - Answer- info coreutils
how to yum install the locate command? - Answer- yum install mlocate make sure to
updatedb
how to find stuff - Answer- rpm -qd <$packageName>
whereis
, which
man
info
things are in /usr/share/doc
/usr/share/info
/usr/share/man
locate and find - Answer- package is mlocate. install httpd also.
updatedb.
find /etc -name motd
find /etc -user <$name>
find / -mtime -3
find / -mtime +3
find / -uid <$uid>
find / -user jeff - type f
find /home/ -user jeff -type f -exec rm {} \;
useful for finding mass compromised files.
how to gain access to a system - Answer- interrupt the boot process to change the
root password on a system.
need physical access to the machine.
reboot
hit any key to interrupt the boot.
select a kernel
hit e to edit the grub config.
grub menu loads local kernel in the memory. needs to be mounted. attached future
disk root drive. nitramfs. initramfs. go to debug shell and code in memory.
linux16 line. end command. type in rd.break. ctrl x
goes into initram debug shell.
go in /sysroot or /root.
/sysroot will be mounted as /root
/sysroot is read only.
mount -oremount,rw /sysroot
chroot /sysroot
passwd
make new passwd.
touch /.autorelabel
exit
exit
system will reboot. we go into root now.
how to view oldest to newest processes of a user as root? - Answer- pgrep -u
<$username> -l
show all processes not owned by user is which pgrep flag? - Answer- -v
what are the flags and differences in pkill SIGKILL and pkill SIGTERM? - Answer- -9
or -SIGKILL and it murders it asap
-15 or -SIGTERM and it allows it to do a clean shutdown
Systems Admin
how to redirect errors to a file? - Answer- command 2> <$filename>
2> will over write the file and 2>> will append
how to redirect both standard error and output to a file and have no outputs show on
screen? - Answer- &>
how to redirect standard error into standard output? - Answer- 2 > &1
how to grep opposites? - Answer- grep -v
select all that do not start with l,i,n,u,x - Answer- grep -v '[^linux]'
returns everything not beginning with the letters: l, i, n, u, x
what does ? mean in regex - Answer- character before is optional
what does + mean in regex - Answer- preceding item is matched 1 or more times
what is scp? - Answer- secure copy protocol. do it over ssh. encrypted. old way to
transfer. can send commands to the other server.
what is sftp? - Answer- secure file transfer protocol. or ssh file transfer protocol. can
connect and live inside the other server.
can type get <$filename> to get copy the files back
what is tar -cvf - Answer- create, verbose, use this archive name.
how to see files in archive - Answer- tar -tf
what does tar -xzvf do - Answer- eXtract gZip Verbosely Filename
star command. archive utility. not default. need to yum install. - Answer- big data sets
and files.
what is apropos and mandb - Answer- apropos searches the titles of man pages for
this key.
man page is not indexed and cached so we need to run mandb and it'll be recorded.
how to see all the commands if stuck - Answer- info coreutils
how to yum install the locate command? - Answer- yum install mlocate make sure to
updatedb
how to find stuff - Answer- rpm -qd <$packageName>
whereis
, which
man
info
things are in /usr/share/doc
/usr/share/info
/usr/share/man
locate and find - Answer- package is mlocate. install httpd also.
updatedb.
find /etc -name motd
find /etc -user <$name>
find / -mtime -3
find / -mtime +3
find / -uid <$uid>
find / -user jeff - type f
find /home/ -user jeff -type f -exec rm {} \;
useful for finding mass compromised files.
how to gain access to a system - Answer- interrupt the boot process to change the
root password on a system.
need physical access to the machine.
reboot
hit any key to interrupt the boot.
select a kernel
hit e to edit the grub config.
grub menu loads local kernel in the memory. needs to be mounted. attached future
disk root drive. nitramfs. initramfs. go to debug shell and code in memory.
linux16 line. end command. type in rd.break. ctrl x
goes into initram debug shell.
go in /sysroot or /root.
/sysroot will be mounted as /root
/sysroot is read only.
mount -oremount,rw /sysroot
chroot /sysroot
passwd
make new passwd.
touch /.autorelabel
exit
exit
system will reboot. we go into root now.
how to view oldest to newest processes of a user as root? - Answer- pgrep -u
<$username> -l
show all processes not owned by user is which pgrep flag? - Answer- -v
what are the flags and differences in pkill SIGKILL and pkill SIGTERM? - Answer- -9
or -SIGKILL and it murders it asap
-15 or -SIGTERM and it allows it to do a clean shutdown
