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Red Hat System Administration I Flashcards (RH124)
Red Hat System Administration I Flashcards (RH124)
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1$ whoami2mohammad1$ pwd2/home/mohammad1# Absolute2/home/mohammad/docs/file.txt3# Relative (from /home/mohammad)4docs/file.txt1$ man ls2$ man 5 passwd # section 5 = file formats1$ whatis ls2ls (1) - list directory contents3$ ls --help1$ history2$ !42 # run command number 423$ !! # repeat last command1$ echo "Hello, World!"2$ echo $HOME3/home/mohammad1$ su - # switch to root (full login shell)2$ sudo dnf update # run one command as root1$ sudo -i2# whoami3root1$ ls -lah /etc1$ mkdir mydir2$ mkdir -p /tmp/a/b/c # creates all parents1$ cp file.txt /tmp/2$ cp -r mydir/ /tmp/mydir_backup/1$ mv old.txt new.txt # rename2$ mv file.txt /tmp/ # move1$ rm file.txt2$ rm -r mydir/3$ rmdir emptydir/1$ touch newfile.txt1$ ln file.txt hardlink.txt # hard link2$ ln -s file.txt softlink.txt # symbolic link1$ find /etc -name "*.conf"2$ find /home -type f -size +10M3$ locate passwd1$ cat /etc/hostname2$ less /var/log/messages3$ head -20 /etc/passwd4$ tail -f /var/log/secure1$ ls /etc > output.txt # overwrite2$ echo "line" >> file.txt # append3$ command 2>/dev/null # discard errors1$ ps aux | grep httpd2$ cat /etc/passwd | wc -l3$ df -h | sort -k5 -rn1$ grep "root" /etc/passwd2$ grep -rn "error" /var/log/3$ grep -v "^#" /etc/ssh/sshd_config1$ wc -l /etc/passwd245 /etc/passwd1# username:x:UID:GID:comment:home:shell2mohammad:x:1000:1000:Mohammad:/home/mohammad:/bin/bash1$ sudo useradd -m -s /bin/bash ali2$ sudo usermod -aG wheel ali # add to wheel group3$ sudo userdel -r ali # delete + home dir1$ sudo passwd ali # set ali's password2$ passwd # change your own password1$ sudo groupadd devteam2$ sudo usermod -aG devteam mohammad3$ sudo groupdel devteam1-rwxr-xr-- 1 root wheel 4096 Jan 1 12:00 script.sh2# owner: rwx, group: r-x, others: r--1$ chmod 755 script.sh # rwxr-xr-x2$ chmod u+x,g-w file.txt # symbolic3$ chmod -R 644 /var/www/html1$ sudo chown ali file.txt2$ sudo chown ali:devteam file.txt3$ sudo chown -R nginx:nginx /var/www/1$ umask # view current umask200223$ umask 027 # set new umask1$ chmod u+s /usr/bin/someprog # SUID2$ chmod g+s /shared/ # SGID on dir3$ chmod +t /tmp # sticky bit1$ ps aux2$ ps -ef3$ top4$ htop1$ kill 1234 # SIGTERM (default)2$ kill -9 1234 # SIGKILL3$ killall httpd4$ pkill -u ali # kill all processes by user1$ sleep 300 & # start in background2$ jobs # list jobs3$ fg %1 # bring job 1 to foreground4$ bg %1 # resume job 1 in background1$ nice -n 10 tar czf backup.tar.gz /data2$ renice -n 5 -p 12341$ pgrep sshd2$ pstree -p1$ ip addr show2$ ip addr show eth03$ ip link show1$ ip route show2default via 192.168.1.1 dev eth01$ nmcli connection show2$ nmcli device status3$ nmcli con up "Wired connection 1"1$ ping -c 4 8.8.8.82$ traceroute google.com3$ ss -tuln # listening ports1127.0.0.1 localhost2192.168.1.10 myserver.local myserver1nameserver 8.8.8.82nameserver 8.8.4.43search example.com1$ ssh mohammad@192.168.1.102$ ssh -p 2222 mohammad@server.example.com1$ ssh-keygen -t ed255192$ ssh-copy-id mohammad@192.168.1.101$ scp file.txt mohammad@server:/tmp/2$ rsync -avz /local/dir/ mohammad@server:/remote/dir/1Host myserver2 HostName 192.168.1.103 User mohammad4 Port 22225 IdentityFile ~/.ssh/id_ed255191$ df -h2$ du -sh /var/log/3$ du -h --max-depth=1 /home/1$ lsblk2$ sudo fdisk -l /dev/sda3$ sudo blkid1$ sudo mkfs.xfs /dev/sdb12$ sudo mkfs.ext4 /dev/sdb21$ sudo mount /dev/sdb1 /mnt/data2$ sudo mount UUID="abc-123" /mnt/data3$ sudo umount /mnt/data1# device mountpoint fstype options dump pass2UUID=abc-123 /data xfs defaults 0 21$ sudo pvcreate /dev/sdb2$ sudo vgcreate datavg /dev/sdb3$ sudo lvcreate -L 10G -n datalv datavg4$ sudo mkfs.xfs /dev/datavg/datalv1$ sudo lvextend -L +5G /dev/datavg/datalv2$ sudo xfs_growfs /data # XFS3$ sudo resize2fs /dev/datavg/datalv # ext41$ sudo mkswap /dev/sdb22$ sudo swapon /dev/sdb23$ free -h4$ swapon --show1$ dnf repolist2$ sudo dnf config-manager --enable codeready-builder3$ ls /etc/yum.repos.d/1$ dnf module list2$ dnf module enable python39:3.93$ dnf module install python391$ dnf history2$ sudo dnf history undo 151$ sudo systemctl enable --now sshd2# equivalent to enable + start in one command1$ systemctl get-default # show default target2$ sudo systemctl set-default multi-user.target3$ sudo systemctl isolate rescue.target1$ systemctl --failed2$ systemctl status httpd.service1[Unit]2Description=My Application3After=network.target4
5[Service]6ExecStart=/usr/local/bin/myapp7Restart=always8
9[Install]10WantedBy=multi-user.target11
12$ sudo systemctl daemon-reload13$ sudo systemctl enable --now myapp1$ sudo mkdir -p /var/log/journal2$ sudo systemctl restart systemd-journald1$ echo $PATH2$ printenv HOME3$ export MYVAR="hello" # set and export1$ MYVAR="local only"2$ export MYVAR # now available to child processes3$ export MYVAR="hello" # set and export in one step1#!/bin/bash2# My first script3echo "Hello, $USER!"4DATE=$(date +%Y-%m-%d)5echo "Today is $DATE"1#!/bin/bash2NAME="Mohammad"3UPTIME=$(uptime -p)4echo "Hello $NAME, uptime: $UPTIME"1#!/bin/bash2if [ -f /etc/passwd ]; then3 echo "File exists"4else5 echo "File not found"6fi1#!/bin/bash2for USER in ali sara omar; do3 echo "Creating user: $USER"4 sudo useradd $USER5done6
7for i in {1..5}; do8 echo "Number: $i"9done1#!/bin/bash2COUNT=13while [ $COUNT -le 5 ]; do4 echo "Count: $COUNT"5 ((COUNT++))6done1#!/bin/bash2echo "Script: $0"3echo "First arg: $1"4echo "All args: $@"5echo "Count: $#"1$ ls /etc2$ echo $? # 0 = success3$ ls /nonexistent4$ echo $? # 2 = error1NAME="Mohammad"2echo '$NAME' # prints: $NAME (literal)3echo "$NAME" # prints: Mohammad (expanded)1$ alias ll='ls -lah'2$ alias grep='grep --color=auto'3$ unalias ll