CHECK!!! bash course
bash course
exit 0
read -a
export VAR not subshell
profile subshells
bashrc user
top kill pid
telnet 0
cat -vet
0 stdin, 1 stdout, 2 stderr
pipeline stdout-)stdin
grep -E '[A-Z][a-z]+\b' file.txt
grep -l n c
grep ^...$ #find any 3 chars
sed -r s c a y I p
whereis
fdisk -l
udev daemon
chntpw
su - vs su
su - logs you in completely as root, whereas su makes it so you are pretending to be root.
mount -o remount,rw /
parted -k
gpt gui uefi partitions )2tb (part 2)
partitions primary extended logical
have compiled your own kernel at some point, know how to trace syscalls, understand TCP, care about the difference between sysvinit/runit/systemd, etc
man 7 signal trap kill term int
substitution operators ${VAR:-word}
pattern matching ${BLA#bla*}
optarg
man test
pncopy
strace -c ls
hup vs kill
var/log/messages centos
rpm qa in ubuntu
yum update apt.get update
redhat satelite ubuntu landscape tools for deployment
root.system.people
sudo su
ls --help show options
cd equal cd ,,~
rm -rf * del current dir
rm -rf / dont do
its not possible to create hardlink to directory or other device, only symbolic link
through inode we got access to data blocks
usermod -Ga group1 user1 ( G override s previous group)
id user
!gre repeat last grep
/etc/shadow !! user locked
chage
etc.login.defs - default password age
chown chgrp change user or group owner
without execute permission you cannot get to directory
without read you cannot ls directory
chmod +x file
chmod u=rw,g-w,o+x file
daemon - systemctl,
jobs
dd if=dev zero of dev null
ctrl z - stop job temporarily
jobs
bg fg
ctrl c terminate job
pstree
top
1.01 bad
wa disk write
ctrl l clean
kill 15 vs 9 in top
default process priority 20, increase by 5
tools used for deployment
ubuntu landscape,redhat satelite, puppet, chef
cttl alt f1 f2 switch terminals
elinks text browser
man -k apropos
man -k time / grep 1
/usr/share/doc pam,rsyslog
man 7 glob
ls -d l*
mail -s subj root < .
grep hi * 2>/dev/tty6
find / -name "*.rpm" > rpm.results 2> /dev/null
ls > files
sort <files >files.sorted
ls -d *[0-9]* doesnt show dir content
which whereis locate updatedb
file etc.tar
tar is used for backups
tar czvf file.tgz
tar + gzip
tar xvf file.tar -C /tmp
tar xvf /root/etc.tar -C / etc/wgetrc
cp /etc/[aef]* /tmp
grep -iR file * 2>/dev/nu search in directories
sed 2q file #show first 2 lines
sed -n '2p' file #same
sed -n /^root/p etc.passwd
grep '^root' etc.passwd
sed -i 's/old/new/g' file
ctrl alt f1,2 open virtual terminal
ssh-keygen
ssh-copy-id -p 2022 user@host
scp ipaddress:port
etc.ssh
ssh_config client
sshd_config server
etc.shadow !! user disabled
etc passwd.
gecos field used to identify the user(sales department)
by default rhel uses private groups
etc.login.defs
etc.default.useradd
etc.skel
ldap
dc=com,dc=rhel,cn=server
ldd login
etc.pam.d
special permissions
suid 4000
guid 2000
sticky 1000
setfacl -R -m g:sales:rx dir
setfacl -m d:g:sales:rx dir
getfacl dir
ip addr flush
ip addr show
ip a
ip route show
#temp
ip route add 20.0.0.0/8 via 192.0.0.1
ip addr add dev env33 192.8.8.8/24
ip -s link
net settings
/etc/sysconfig/network-scripts
vim ifcfg-ens33
etc/hostname is used now by linux instead of etc/sysconf
network manager gets conf from sysconf and pushes to
etc/resolve.conf #dont change here
nmcli,nmtui
after changing nmtui do systemctl restart NetworkManager
nmcli con down ems32; nmcli com up ems33
dig
nmap
netstat
traceroute
ip -s link
jobs are related to current shell environment
ctrl z
jobs
bg #runs last job
sleep 600 & # run in background
fg 1
ctrl c terminate job
w shows terminal
ps fax parent process
free -m #m stands mb
top show cpus press 1
cachd is used for files .disk speed
use sigterm 15 over sigkil 9
killall sleep . all processes with name dd
nohup
https://www.google.com.ua/amp/
name nohup stands for "no hangup." The hangup (HUP) signal, which is normally sent to a process to inform it that the user has logged off (or "hung up"), is intercepted by nohup, allowing the process to continue running.
standard input is a terminal, nohup redirects it from /dev/null. If standard output is a terminal, append output to "nohup.out" if possible, "$HOME/nohup.out" otherwise. If standard error is a terminal, redirect it to standard output. To save output to file FILE, use "nohup COMMAND > FILE".
by default process priority 20
nice -20 to 19
pgrep -a dd
renice -n 5 pid
yum meta package handler
cd /etc/yum.repos.d
vim myrepo.repo
[myrepo]
name=myrepo
baseurl=file:///repo
gpgcheck=0
yum repolist
yum search ftp
yum list all
yum list installed
yum whatprovides */semanage
yum removd bash
all installed software via rpm database
which chronyd
rpm -qf /sbin/chronyd
rpm -ql chronyd
rpm -qc chrony #config files involved
rpm -qd chrony #documentation
rpm -qa #all installed packages
rpm -q --scripts httpd #install postinstall script.security
yum localinstall packagename
repoquery
dd if=/dev/sr0 of=/root/rhel.iso # command to create iso
cat /etc/crontab
cd /etc/cron.daily
crontab -e or put file to /etc/crontab.d
systemctl list-units -t service (ubuntu>14)
atq
atrm
/var/spool/at
/var/log/messages
systemctl daemon-reload
____
daemon-reload¶
Reload the systemd manager configuration. This will rerun all generators (see systemd.generator(7)), reload all unit files, and recreate the entire dependency tree. While the daemon is being reloaded, all sockets systemd listens on behalf of user configuration will stay accessible.
This command should not be confused with the reload command.
_____
cat /proc/partitions
1mb partition meta data
in fdisk 1mb 1000kb, 1mib 1024kb
partitions are created with fdisk
file system is created with mkfs.xxx
mount /dev/sdb1 /mnt
/mnt used for testing mounting
mount - shows mounted devices
mount ! grep ^dev
umount /mnt
blkid - show devices and uuid
mount LABEL=myfs /mount
classic way to mount filesystem automatically is to use etc/fstab
mount -a
mounts what wasnt mounted
journalctl -xb
journalctl -f
rhel var.messsges var.secure
ubuntu var.syslog
ubuntu
systemctl status rsyslog
etc.rsyslog.cong info.warn.error
in rhel7 there are no run levrls but systemd targets
ln -sf
-------
useradd linda
cd /home/linda
touch rootsfile
su - linda
rm -f rootsfile
if user has write permissions on directory,he can delete files
-------
dont change unit files in usrbin folder,copy to etc
dont need to copy back from etc to usrbin
__
locate updatedb
hard link can only be created if it refers to a file in the same file system. This is because inodes are unique to a file system. Links that cross file system boundaries must be symbolic links.
https://en.m.wikipedia.org/
ls -s -h
firewalls
ufw and iptables ubuntu
firewalld and iptables rhel
firewalld runtime config,not persistent
to add in runtime and persistent
firewall-cmd --add-service ldap --permanent
--list-all
--get-services
repquota
disown -r
remove running jobs
compgen -c list of commands
rpm -e sendmail #uninstall
show the status of all Linux kernel modules currently loaded:
lsmod
exit 0
read -a
export VAR not subshell
profile subshells
bashrc user
top kill pid
telnet 0
cat -vet
0 stdin, 1 stdout, 2 stderr
pipeline stdout-)stdin
grep -E '[A-Z][a-z]+\b' file.txt
grep -l n c
grep ^...$ #find any 3 chars
sed -r s c a y I p
whereis
fdisk -l
udev daemon
chntpw
su - vs su
su - logs you in completely as root, whereas su makes it so you are pretending to be root.
mount -o remount,rw /
parted -k
gpt gui uefi partitions )2tb (part 2)
partitions primary extended logical
have compiled your own kernel at some point, know how to trace syscalls, understand TCP, care about the difference between sysvinit/runit/systemd, etc
man 7 signal trap kill term int
substitution operators ${VAR:-word}
pattern matching ${BLA#bla*}
optarg
man test
pncopy
strace -c ls
hup vs kill
var/log/messages centos
rpm qa in ubuntu
yum update apt.get update
redhat satelite ubuntu landscape tools for deployment
root.system.people
sudo su
ls --help show options
cd equal cd ,,~
rm -rf * del current dir
rm -rf / dont do
its not possible to create hardlink to directory or other device, only symbolic link
through inode we got access to data blocks
usermod -Ga group1 user1 ( G override s previous group)
id user
!gre repeat last grep
/etc/shadow !! user locked
chage
etc.login.defs - default password age
chown chgrp change user or group owner
without execute permission you cannot get to directory
without read you cannot ls directory
chmod +x file
chmod u=rw,g-w,o+x file
daemon - systemctl,
jobs
dd if=dev zero of dev null
ctrl z - stop job temporarily
jobs
bg fg
ctrl c terminate job
pstree
top
1.01 bad
wa disk write
ctrl l clean
kill 15 vs 9 in top
default process priority 20, increase by 5
tools used for deployment
ubuntu landscape,redhat satelite, puppet, chef
cttl alt f1 f2 switch terminals
elinks text browser
man -k apropos
man -k time / grep 1
/usr/share/doc pam,rsyslog
man 7 glob
ls -d l*
mail -s subj root < .
grep hi * 2>/dev/tty6
find / -name "*.rpm" > rpm.results 2> /dev/null
ls > files
sort <files >files.sorted
ls -d *[0-9]* doesnt show dir content
which whereis locate updatedb
file etc.tar
tar is used for backups
tar czvf file.tgz
tar + gzip
tar xvf file.tar -C /tmp
tar xvf /root/etc.tar -C / etc/wgetrc
cp /etc/[aef]* /tmp
grep -iR file * 2>/dev/nu search in directories
sed 2q file #show first 2 lines
sed -n '2p' file #same
sed -n /^root/p etc.passwd
grep '^root' etc.passwd
sed -i 's/old/new/g' file
ctrl alt f1,2 open virtual terminal
ssh-keygen
ssh-copy-id -p 2022 user@host
scp ipaddress:port
etc.ssh
ssh_config client
sshd_config server
etc.shadow !! user disabled
etc passwd.
gecos field used to identify the user(sales department)
by default rhel uses private groups
etc.login.defs
etc.default.useradd
etc.skel
ldap
dc=com,dc=rhel,cn=server
ldd login
etc.pam.d
special permissions
suid 4000
guid 2000
sticky 1000
setfacl -R -m g:sales:rx dir
setfacl -m d:g:sales:rx dir
getfacl dir
ip addr flush
ip addr show
ip a
ip route show
#temp
ip route add 20.0.0.0/8 via 192.0.0.1
ip addr add dev env33 192.8.8.8/24
ip -s link
net settings
/etc/sysconfig/network-scripts
vim ifcfg-ens33
etc/hostname is used now by linux instead of etc/sysconf
network manager gets conf from sysconf and pushes to
etc/resolve.conf #dont change here
nmcli,nmtui
after changing nmtui do systemctl restart NetworkManager
nmcli con down ems32; nmcli com up ems33
dig
nmap
netstat
traceroute
ip -s link
jobs are related to current shell environment
ctrl z
jobs
bg #runs last job
sleep 600 & # run in background
fg 1
ctrl c terminate job
w shows terminal
ps fax parent process
free -m #m stands mb
top show cpus press 1
cachd is used for files .disk speed
use sigterm 15 over sigkil 9
killall sleep . all processes with name dd
nohup
https://www.google.com.ua/amp/
name nohup stands for "no hangup." The hangup (HUP) signal, which is normally sent to a process to inform it that the user has logged off (or "hung up"), is intercepted by nohup, allowing the process to continue running.
standard input is a terminal, nohup redirects it from /dev/null. If standard output is a terminal, append output to "nohup.out" if possible, "$HOME/nohup.out" otherwise. If standard error is a terminal, redirect it to standard output. To save output to file FILE, use "nohup COMMAND > FILE".
by default process priority 20
nice -20 to 19
pgrep -a dd
renice -n 5 pid
yum meta package handler
cd /etc/yum.repos.d
vim myrepo.repo
[myrepo]
name=myrepo
baseurl=file:///repo
gpgcheck=0
yum repolist
yum search ftp
yum list all
yum list installed
yum whatprovides */semanage
yum removd bash
all installed software via rpm database
which chronyd
rpm -qf /sbin/chronyd
rpm -ql chronyd
rpm -qc chrony #config files involved
rpm -qd chrony #documentation
rpm -qa #all installed packages
rpm -q --scripts httpd #install postinstall script.security
yum localinstall packagename
repoquery
dd if=/dev/sr0 of=/root/rhel.iso # command to create iso
cat /etc/crontab
cd /etc/cron.daily
crontab -e or put file to /etc/crontab.d
systemctl list-units -t service (ubuntu>14)
atq
atrm
/var/spool/at
/var/log/messages
systemctl daemon-reload
____
daemon-reload¶
Reload the systemd manager configuration. This will rerun all generators (see systemd.generator(7)), reload all unit files, and recreate the entire dependency tree. While the daemon is being reloaded, all sockets systemd listens on behalf of user configuration will stay accessible.
This command should not be confused with the reload command.
_____
cat /proc/partitions
1mb partition meta data
in fdisk 1mb 1000kb, 1mib 1024kb
partitions are created with fdisk
file system is created with mkfs.xxx
mount /dev/sdb1 /mnt
/mnt used for testing mounting
mount - shows mounted devices
mount ! grep ^dev
umount /mnt
blkid - show devices and uuid
mount LABEL=myfs /mount
classic way to mount filesystem automatically is to use etc/fstab
mount -a
mounts what wasnt mounted
journalctl -xb
journalctl -f
rhel var.messsges var.secure
ubuntu var.syslog
ubuntu
systemctl status rsyslog
etc.rsyslog.cong info.warn.error
in rhel7 there are no run levrls but systemd targets
ln -sf
-------
useradd linda
cd /home/linda
touch rootsfile
su - linda
rm -f rootsfile
if user has write permissions on directory,he can delete files
-------
dont change unit files in usrbin folder,copy to etc
dont need to copy back from etc to usrbin
__
locate updatedb
hard link can only be created if it refers to a file in the same file system. This is because inodes are unique to a file system. Links that cross file system boundaries must be symbolic links.
https://en.m.wikipedia.org/
ls -s -h
firewalls
ufw and iptables ubuntu
firewalld and iptables rhel
firewalld runtime config,not persistent
to add in runtime and persistent
firewall-cmd --add-service ldap --permanent
--list-all
--get-services
repquota
disown -r
remove running jobs
compgen -c list of commands
rpm -e sendmail #uninstall
show the status of all Linux kernel modules currently loaded:
lsmod
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