# Rocky Linux ![](/files/6UTjWbEb5kYDntkpg37Z) > 📌 *These are Linux commands notes taken from the Rocky Linux docs, maybe I'll move them to a more Linux general section later.* *** ## 🌐 Resources 🔗 > * [Rocky Linux](https://rockylinux.org/) > * [Rocky Linux Instructional Books - Documentation](https://docs.rockylinux.org/books/) > * [VI Text editor - Documentation](https://docs.rockylinux.org/books/admin_guide/05-vi/) ### 📚 [The UNIX/Linux Philosophy](https://docs.rockylinux.org/books/admin_guide/01-presentation/#the-unixlinux-philosophy) * Treat everything as a file. * Value portability. * Do one thing and do it well. * **KISS**: Keep It Simple Stupid. * "UNIX is a simple operating system, but you have to be a genius to understand the simplicity." (Dennis Ritchie) * "Unix is user-friendly. It just isn't promiscuous about which users it's friendly with." (Steven King) *** ## Commands ```bash # command [option(s)] [argument(s)] /bin/bash cat /etc/passwd cat /etc/shadow cat /etc/profile cat /etc/sudoers apropos --exact password -a change whatis clear man clear reboot shutdown -r +5 shutdown now shutdown -h 0:30 shutdown -h 0:30 "Server shutdown at 0:30" shutdown --show shutdown -c history clear echo -ne "\t Hello \n" echo $LANG echo $PATH date date +%F date +%x date +%T date -d 20250310 +%j # Convert timestamp to a date date -d "1970-01-01 20156 days" # Convert date to timestamp echo $(($(date --date="2025-01-25" +%s)/86400+1)) id root whoami who who -r pwd cd ls ls -l ls -ld ls -lX ls -g ls -dl ls -lah ls -ltr ls -lhS ls -lhR ls -liah ls -lAhR ls -lhR /var/ | grep ^\- | grep -E "[1-9]*\.[0-9]*M" alias ll du -sh /etc mkdir -p /tmp/newdir/newsubdir touch file touch -t [AAAA]MMJJhhmm[ss] file rmdir /tmp/newdir/newsubdir rm file rm -r dir rm -rf dir/files rm -f -- -file mv file1 file2 mv file1 file2 /tmp cp file1 file2 cp file /tmp cp -pr dir1 dir2 file /etc/passwd more /etc/passwd less file1 /text # search g or G # first/last page cat /etc/passwd cat -n /etc/passwd cat -b /etc/profile cat /etc/passwd /etc/group tac /var/log/messages | less head -n 20 /etc/profile tail -n 20 /etc/profile tail -f /var/log/messages sort -k 3,4 -t ":" -n /etc/passwd sort -u FILE sort FILE | uniq sort -nr ips.txt sort -hr size.txt wc -c wc -l find /tmp -name *.txt -exec rm -f {} \; find /tmp -name *.txt -delete find /var -size +1M -a -size -1024M -a -type f -exec ls -lh {} \; whereis ls which ls grep "root*" /etc/passwd grep -w "root:" /etc/passwd grep -w "^root" /etc/passwd grep -i version /etc/os-release grep -iv version /etc/os-release grep -R "systemd" /var/log/ ``` ```bash # Input redirection ftp -in serverftp << ftp-commands.txt wc -l /etc/profile wc -l < /etc/profile # Output redirection date +%F > date_file # overwrite date +%F >> date_file # append # stderr output redirection ls -R / 2> errors_file ls -R / >> ok_file 2>> nok_file ls -R / >> log_file 2>&1 ls -R / 2>> /dev/null # Copy stdin to file and to stdout cat /etc/os-release | tee release # Pipes ls -lia / | head ls -lia / | tail ls -lia / | sort ls -lia / | wc ls -lia / | grep etc ls -lia / | tee list # Aliases alias cat .bashrc # permanent user's aliases file cat /etc/bashrc # all users file type ls ls \ls mount | column -t ls /; cd /home; ls -lia; cd / ``` ```bash sort firstnames.txt | uniq sort firstnames.txt | uniq -cd xargs ls -ld /home /tmp xargs -L 1 find /var/log -name xargs -n 1 find /var/log -name find /var/log/ -name "*.log" -mtime -1 | xargs tar cvfP /root/log.tar mkdir /tmp/backup && find /var/log -type f -name "*.log" | xargs -I % cp % /tmp/backup watch watch -n 5 tail -n 5 /var/log/secure watch -n 1 'ls -l | wc -l' watch -t -n 1 date install -d /tmp/samples install /tmp/test.txt /tmp/samples/ install -v -o syselement -g users -m 644 -D -t /tmp/samples/ /tmp/test.txt install -v -b -S ".bak" -D -t /tmp/samples/ /tmp/test.txt tree tree -ah tree -hugp /etc/security/ stat /var/log/messages ``` ```bash # yum/dnf # yum-utils / dnf-utils package dnf install dnf-utils repoquery repoquery -l yum-utils rpm -ql yum-utils # same yumdownloader --destdir /var/tmp/ --resolve samba dnf download --downloadonly --downloaddir /var/tmp --resolve samba # same # pmisc package pstree killall nc fuser ``` ### User management ```bash # Files /etc/passwd /etc/shadow /etc/group /etc/gshadow /etc/skel/ /etc/default/useradd /etc/login.defs ``` ```bash # Groups cat /etc/group cat /etc/gshadow groupadd -g 1020 group1 # Debian addgroup groupmod -g 1022 group1 groupmod -n group3 group2 sudo find / -gid 1020 -exec chgrp 1022 {} \; groupdel group1 # root GID = 0 gpasswd -a user2 group1 gpasswd -d user2 group1 echo $SHLVL ; echo $BASH_SUBSHELL newgrp group1 # child shell with temp group1 ``` ```bash # Users # root (uid=0) - system admin # system users (uid=201~999) # regulare users (uid>=1000) cat /etc/passwd cat /etc/shadow # ! For each line in the /etc/passwd file there must be a corresponding line in the /etc/shadow file. # default settings ls -lah /etc/skel/ # file templates for new user home dir cat /etc/login.defs cat /etc/default/useradd useradd -D # shows /etc/default/useradd contents useradd user1 # defaults from /etc/default/useradd useradd -N user1 # no user group, uses the default (users:100) useradd -u 1002 -g 1020 -d /home/user user2 passwd user1 tail -n 2 /etc/passwd tail -n 2 /etc/shadow tail -n 2 /etc/group ; tail -n 2 /etc/gshadow # Debian adduser deluser usermod -u 1005 user1 usermod -L user2 # lock user usermod -G user1 user2 userldel -r user1 # deletes user's home dir, mail files and primary group # File owners chown user1 file chown :group1 file chown user1:group1 file chown -R -v user1:group1 /tmp/dir chown --reference=./file2 file chgrp group1 file ``` ```bash passwd passwd user1 passwd -S user1 passwd -l user1 # lock user passwd -u user1 # unlock user sudo echo "p@ssw0rd" | passwd --stdin user1 # default pw, e.g. in scripts chage user1 chage -m 60 -M 90 -W 80 -I 10 user1 # pw expire su # login as root su - user1 # - = -l = make the shell a login shell su - root -c "cat /etc/shadow" ``` ### File system | Directory | Functionality | Complete word | | ---------- | ---------------------------------------------------------------------------------------------------------------- | ----------------------------- | | `/` | Contains special directories | | | `/boot` | Files related to system startup | | | `/sbin` | Commands necessary for system startup and repair | *system binaries* | | `/bin` | Executables of basic system commands | *binaries* | | `/usr/bin` | System administration commands | | | `/lib` | Shared libraries and kernel modules | *libraries* | | `/usr` | Saves data resources related to UNIX | *UNIX System Resources* | | `/mnt` | Temporary mount point directory | *mount* | | `/media` | For mounting removable media | | | `/misc` | To mount the shared directory of the NFS service. | | | `/root` | Administrator's login directory | | | `/home` | The upper-level directory of a common user's home directory | | | `/tmp` | The directory containing temporary files | *temporary* | | `/dev` | Special device files | *device* | | `/etc` | Configuration and script files | *editable text configuration* | | `/opt` | Specific to installed applications | *optional* | | `/proc` | This is a mount point for the proc filesystem, which provides information about running processes and the kernel | *processes* | | `/var` | This directory contains files which may change in size, such as spool and log files | *variables* | | `/sys` | Virtual file system, similar to /proc | | | `/run` | That is /var/run | | | `/srv` | Service Data Directory | *service* | ```bash ls -lah /dev/ # (Standard) Partitions cat /proc/partitions fdisk -l fdisk -l /dev/nvme0n1 cfdisk /dev/nvme0 # optimized, to managed partitions parted parted -l /dev/nvme0 gparted # GUI lsblk dmsetup ls # Disk preparation steps (no LVM) # 1. Physical disk setup # 2. Volumes partitioning # 3. File systems creation # 4. File systems mounting # 5. User access management ``` |

LVM STORAGE
MECHANISMS

| Performance | Redundancy | Space Efficiency | Use Case | | -------------------------------- | ----------- | ---------- | ---------------- | ------------------------- | | Linear | Normal | ❌ No | ✅ High | Basic storage growth | | Striped | ✅ High | ❌ No | ✅ High | Fast I/O, performance | | Mirrored | Moderate | ✅ Yes | ❌ Low | Data safety, critical use | ```bash # LVM - Logical Volume Manager # PV (Physical Volume): Raw storage (disk/partition) # PE (Physical Extent): Chunk of space in PVs # VG (Volume Group): Pool of storage from PVs # LV (Logical Volume): Usable partitions created from VG # FS (File System): each LV can be formatted (ext4, xfs, ...) # PV commands pvscan pvcreate pvdisplay pvremove pvs # VG commands vgscan vgcreate vgdisplay vgremove vgextend vgreduce vgs # LV commands lvscan lvcreate lvdisplay lvremove lvextend lvreduce lvs # DISK PREPARATION # 0. Prepare Physical disk and Partitions (if necessary) # check for existing LVM volumes pvs vgs lvs # Wipe nvme0n2 disk - WIPES ALL LVM/DATA/HEADERS! wipefs --all --force /dev/nvme0n2 dd if=/dev/zero of=/dev/nvme0n2 bs=1M count=100 # dd if=/dev/zero of=/dev/nvme0n2 bs=1M status=progress # ^^^ OWERWRITES ENTIRE DISK (SLOW) ^^^ hexdump -C /dev/nvme0n2 # should be clean # Create new GPT partition table on disk nvme0n2 parted /dev/nvme0n2 mklabel gpt # create single primary partition on disk nvme0n2 parted /dev/nvme0n2 mkpart primary 1MiB 100% fdisk -l /dev/nvme0n2 # Disk /dev/nvme0n2: 5 GiB, 5368709120 bytes, 10485760 sectors # Disk model: VMware Virtual NVMe Disk # Units: sectors of 1 * 512 = 512 bytes # Sector size (logical/physical): 512 bytes / 512 bytes # I/O size (minimum/optimal): 512 bytes / 512 bytes # Disklabel type: gpt # Disk identifier: 34A69BE9-CA31-4ADC-B30A-AE22BB47A281 # # Device Start End Sectors Size Type # /dev/nvme0n2p1 2048 10483711 10481664 5G Linux filesystem # ------ 1. LVM Physical Volume (no partitions case) ------ lsblk pvcreate /dev/nvme0n2p1 pvdisplay /dev/nvme0n2p1 # --- NEW Physical volume --- # PV Name /dev/nvme0n2p1 # VG Name # PV Size <5.00 GiB # Allocatable NO # PE Size 0 # Total PE 0 # Free PE 0 # Allocated PE 0 # PV UUID b6bQp6-57SG-vTST-wu3r-F2r7-z5ML-FHHV8W # ------ 2. LVM Volume Group ------ vgcreate vol2 /dev/nvme0n2p1 vgdisplay /dev/vol2 # --- Volume group --- # VG Name vol2 # System ID # Format lvm2 # Metadata Areas 1 # Metadata Sequence No 1 # VG Access read/write # VG Status resizable # MAX LV 0 # Cur LV 0 # Open LV 0 # Max PV 0 # Cur PV 1 # Act PV 1 # VG Size <5.00 GiB # PE Size 4.00 MiB # Total PE 1279 # Alloc PE / Size 0 / 0 # Free PE / Size 1279 / <5.00 GiB # VG UUID cGPnl2-e1Xx-JF7l-uS8r-KmAa-NwX9-LLcxFo # ------ 3. LVM Logical Volume ------ # lvcreate -L 5G -n lv2 vol2 lvcreate -l 100%FREE -n lv2 vol2 lvdisplay /dev/vol2/lv2 # --- Logical volume --- # LV Path /dev/vol2/lv2 # LV Name lv2 # VG Name vol2 # LV UUID DZ3CCM-twpf-arLX-JYt7-9BQE-zoKq-Os5NxE # LV Write Access read/write # LV Creation host, time rockyvm, 2025-05-01 10:00:40 +0200 # LV Status available # # open 0 # LV Size <5.00 GiB # Current LE 1279 # Segments 1 # Allocation inherit # Read ahead sectors auto # - currently set to 8192 # Block device 253:2 # ------ 4. File System creation/mounting ------ # ext2, ext3, ext4, FAT16, FAT32, NTFS, HFS, BtrFS, JFS, XFS, ... mkfs -t xfs /dev/vol2/lv2 blkid /dev/vol2/lv2 # /dev/vol2/lv2: UUID="fc6f54cc-e718-45e4-9620-169bdcd143ce" TYPE="xfs" mkdir -p /mnt/lv2 echo 'UUID=fc6f54cc-e718-45e4-9620-169bdcd143ce /mnt/lv2 xfs defaults 0 2' | tee -a /etc/fstab systemctl daemon-reload mount -a df -hT /mnt/lv2 # Filesystem Type Size Used Avail Use% Mounted on # /dev/mapper/vol2-lv2 xfs 5.0G 68M 4.9G 2% /mnt/lv2 # Final check Disk -> PV -> VG -> LV -> FS echo "=== LVM ===" && pvs && vgs && lvs && echo "=== Disks ===" && lsblk -f && echo "=== Mounts ===" && findmnt ``` ```bash # Boot sector -> Super Block -> inodes table -> Data block # In Linux, everything is a file. # Linux meets the FHS (Filesystems Hierarchy Standard) man hier # Check file system consistency - partition must be UNmounted umount /mnt/lv2 fsck -V /dev/vol2/lv2 xfs_repair -v /dev/vol2/lv2 # Mount point automatically mounted at boot time cat /etc/fstab # /dev/mapper/rl-root / xfs defaults 0 0 # UUID=652d402b-d797-4b8f-94f1-ba39a3537811 /boot xfs defaults 0 0 # /dev/mapper/rl-swap none swap defaults 0 0 # UUID=fc6f54cc-e718-45e4-9620-169bdcd143ce /mnt/lv2 xfs defaults 0 2 # UUID = Universally Unique Identifier lsblk -o name,uuid # Mount all filesystems mentioned in /etc/fstab systemctl daemon-reload mount mount -a # mounted info written to /etc/mtab cat /etc/mtab mount man 8 mount # mount -o defaults = mount -o rw,suid,dev,exec,auto,nouser,async umount /mnt/lv2 # e.g. Temporary mount mkdir -p /mnt/usb mount -t vfat /dev/sdb1 /mnt/usb cd /mnt/usb/ umount /mnt/usb ``` ```bash # ------ File naming ------ mkdir "dir_1" touch .hidden_file # .c : source file in C language # .h : C and Fortran header file # .o : object file in C language # .tar : data file archived with the tar utility # .cpio : data file archived with the cpio utility # .gz : data file compressed with the gzip utility # .tgz : data file archived with the tar utility and compressed with the gzip utility # .html : web page ls -liah /usr/bin/passwd # 9317257 -rwsr-xr-x. 1 root root 32K May 15 2022 /usr/bin/passwd # 1 2 3 4 5 6 7 8 9 # 1 Inode number # 2 File type (1st character of the block of 10). "-" = ordinary file # 3 Access rights (last 9 characters of the block of 10) # 4 Directories: entry/subdirs count. Files: hard link count (1 = single link) # 5 Owner name # 6 Group name # 7 Size (byte, kilo, mega) # 8 Date of last update # 9 Name of the file # ------ 7 File types in GNU/Linux ------ # . Current directory # .. Parent directory # - Regular file (text, binary, data, compressed) # d Directory # b Block device (disks, USBs) # c Character device (keyboard, mouse) # s Socket (network IPC) # p Pipe/FIFO (inter-process communication). FIFO = First-In-First-Out # l Symbolic/soft/hard link (like a shortcut) ls -ld # dr-xr-x---. 3 root root 4096 May 1 11:57 . ls -la # dr-xr-x---. 3 root root 4096 May 1 11:57 . # dr-xr-xr-x. 18 root root 235 Mar 9 14:37 .. ls -l /dev/nvme0n1 # brw-rw----. 1 root disk 259, 0 May 1 09:29 /dev/nvme0n1 ls -l /dev/tty # crw-rw-rw-. 1 root tty 5, 0 May 1 08:28 /dev/tty ls -l /etc/grub2.cfg # lrwxrwxrwx. 1 root root 22 Mar 18 12:41 /etc/grub2.cfg -> ../boot/grub2/grub.cfg # ------ e.g. Soft and Hard links ------ touch original.txt # Create a soft (symbolic) link ln -s original.txt softlink.txt ls -l # -rw-r--r--. 1 root root 0 May 1 17:59 original.txt # lrwxrwxrwx. 1 root root 12 May 1 18:00 softlink.txt -> original.txt # Delete original file, soft link breaks rm original.txt ls -l # softlink.txt points to nothing (broken, in red) # Create a hard link touch fileA ln fileA hardlinkA ls -li # Same inode, hardlinkA and fileA are indistinguishable # 8835024 -rw-r--r--. 2 root root 0 May 1 18:02 fileA # 8835024 -rw-r--r--. 2 root root 0 May 1 18:02 hardlinkA # Remove one, the other still works rm fileA cat hardlinkA # File content still exists # Hard link to directories is not allowed ``` ```bash # ------ File attributes ------ # Basic file/directory permissions # r / 4 = read (file: view, dir: list) # w / 2 = write (file: edit, dir: create/delete) # x / 1 = execute (file: run, dir: cd into) # - / 0 = no right/access ls -l # -rwxr-xr-- # └──┴──┴── owner, group, others # User types # u = owner # g = owner group # o = others users # a = all (u+g+o) # ------ Octal representation ------ # USER GROUP OTHER # +--------+ +--------+ +--------+ # Read (r) | 4 | | 4 | | 4 | # Write(w) | 2 | | 0 | | 0 | # Exec (x) | 1 | | 1 | | 1 | # +--------+ +--------+ +--------+ # Total: 4+2+1 = 7 4+0+1 = 5 4+0+1 = 5 # Octal permission: 755 → rwxr-xr-x chmod 755 file.sh # rwxr-xr-x chmod -R 644 /data # recursive, files: rw-r--r-- # ------ Symbolic representation ------ # Who? Symbol # --------------------- # User u # Group g # Other o # All a # # Operation Symbol # --------------------- # Add + # Remove - # Replace = # # Rights Symbol # --------------------- # Read r # Write w # Execute x chmod u+x file # add execute to owner chmod u+rwx,g+wx,o-r file # remove write from group, read from others chmod -R a=r folder/ # add read for all recursively # ------ Rights and mask (default permissions) ------ # Default Permissions Calculation # -------------------------------------------------------------------------------- # | Type | Max Rights | Umask | Effective Rights | -x Bits | Final Rights | # |------------|------------|-------|------------------|---------|---------------| # | Directory | 777 | 022 | 755 (rwxr-xr-x) | - | 755 | # | File | 666* | 022 | 644 (rw-r--r--) | remove x| 644 | # -------------------------------------------------------------------------------- # # * Note: Max rights for files is 666 (rw-rw-rw-) because execute (x) is not granted # by default when creating a file, for security reasons. # # Explanation: # - Max Rights: theoretical full permissions (777 for dirs, 666 for files) # - Umask: subtracts permission bits (e.g. 022 removes write for group/others) # - -x Bits: execution bits are removed from files even if umask allows them # - Final Rights: resulting permissions on creation umask man umask help umask # 0022 = permissions 755 (rwxr-xr-x) umask -S # u=rwx,g=rx,o=rx - symbolic/file rights # e.g. umask 027 # new files for current session: 640, dirs: 750 touch test.txt ls -l test.txt # -rw-r----- # /etc/login.defs file defines the default UMASK grep -Ri umask /etc/login.defs # Config persistence for custom umask # ~/.bashrc (particular user) # /etc/bashrc and /etc/profile (all users) # ^^^ these overrides the umask parameter of /etc/login.defs ``` ### Process management ```bash # PID = Process IDentifier # PPID = Parent Process IDentifier # "init" process = father of all processes # Parent/Child relationship between processes ps ps -ef ps -fu root # Show processes in the same session (process group) ps -g $(ps -o sess= -p $$) # Show processes associated with a specific terminal (e.g., pts/0 or tty1) ps -t pts/0 # Show process info for a specific PID (replace 1234 with actual PID) ps -p 1234 # Display processes in a hierarchical tree structure (parent/child) ps -H # Long format: includes PPID, priority, nice, etc. ps -l ps -f # Sort by memory usage (descending) ps aux --sort=-%mem # Show headers on each paginated page (useful with 'less') ps aux --headers | less # Custom output format: show PID, UID, and command ps --format "pid,uid,cmd" ps -e --format "%P %p %c %n" --sort ppid --headers # PPID PID COMMAND NI # 0 1 systemd 0 # 0 2 kthreadd 0 # 1 629 systemd-journal 0 # 1 643 systemd-udevd 0 # 1 724 auditd -4 # 1 757 dbus-broker-lau 0 # 1 765 firewalld 0 ``` ```bash # ------ Process types ------ # User process: # - Started from terminal # - Linked to a user session # - Accesses resources via system daemons # # Daemon (System process): # - Started by system (boot time) # - No controlling terminal (TTY) # - Owned by system/root # - Often ends in 'd' (e.g., sshd, systemd) # DAEMON = Disk And Execution MONitor # ------ Permissions & rights ------ # When a user runs a command: # - Real UID/GID = user ID # - Effective process UID/GID = same as real UID/GID # # If SUID/SGID is set on a command: # - Effective process UID/GID = owner/group of the commmand file # - Real UID != Effective UID # - Used for privileged commands (e.g., passwd) # ------ Process states ------ # ready - waiting for CPU time slice/process availability # running/in execution - actively using CPU # suspended - waiting for I/O # stopped - paused by signal (e.g., SIGSTOP), waiting for a signal # zombie - request for destruction # dead - terminated by the parrent process # orphan - child of dead parent process, adopted by init # ------ Process exit sequence ------ # On termination: # - Closes all open files # - Frees allocated memory # - Sends signal to parent (SIGCHLD) # - Orphaned children processes get adopted (and eventually destroyed) by init (PID 1) # ------ Priorities and scheduling ------ # Real-time processes: # - Priority range: 0–99 # - Scheduled with real-time scheduling algorithms # # Normal/ordinary processes: # - Priority range: 100–139 (dynamic) # - Scheduled by Completely Fair Scheduler (CFS) # # Nice value - to adjust the priority of an ordinary process: # - Range: -20 (high priority) to 19 (low) # - Default: 0 nice -n 10 ./myscript.sh # run with adjusted priority # ------ Execution modes ------ # Synchronous: # - Shell waits until command completes # - Must wait the end of the process for command prompt # Asynchronous: # - Shell returns prompt immediately # - Use '&' to run in background sleep 5 & # Constraints for async: # - Must not wait for user input # - Should not output to terminal # - Will terminate when shell exits unless disowned or protected (e.g., nohup) # Sends a signal to a process by PID pidof bash kill -9 23998 kill -19 23999 # Common signals: # 2 SIGINT - Interrupt (Ctrl+C) # 9 SIGKILL - Force kill # 15 SIGTERM - Graceful stop # 18 SIGCONT - Resume # 19 SIGSTOP - Suspend (Ctrl+Z) # List all signals man 7 signal # Run process immune to hangup (connection logout) nohup ./myprogram.sh 0 list.ls 2> /dev/null & # [job_number] PID # fg [job] – bring job to foreground # bg [job] – resume suspended job in background fg 1 # CTRL+Z a synchronous process, then place it in the background bg 1 # Lists background jobs and their status jobs # [1]- Running sleep 1000 # [2]+ Stopped find / # Start a command with adjusted priority (niceness) nice -n -5 find / -name "file" # Higher priority nice -n 5 find / -name "file" # Lower priority nice find / -name "file" # Default (niceness = 10) # Limits file cat /etc/security/limits.conf # Change priority of a running process renice -n 15 -p 24156 # Example using xargs: pidof sleep | xargs renice -n 20 # Real-time process monitor top # pgrep – find PID(s) by name pgrep -u root sshd # pkill – send SIGTERM (default) signal to process by name pkill tomcat # Kill user session according to the terminal number pkill -t pts/1 # Kill all processes with a given name killall tomcat # Show process tree pstree -pnhu # Orphan: parent dies -> init (PID 1) adopts child # Zombie: child exits but parent has not reaped it # Check for zombies: ps -lef | awk '{print $2}' | grep Z # Process state codes: # D - uninterruptible sleep # R - running/runnable # S - sleeping # T - stopped # t - traced (debug) # Z - zombie # X - dead ``` ### Backup and restore ```bash ``` *** ## Terminal Keyboard shortcuts > * [bash - readline interaction](https://www.gnu.org/software/bash/manual/html_node/Readline-Interaction.html) > * [21 Useful Linux Terminal Shortcuts Pro Users Love](https://itsfoss.com/linux-terminal-shortcuts/) ```bash Ctrl + A # Move to the start of the line. Ctrl + E # Move to the end of the line. Ctrl + U # Delete from the cursor to the start of the line. Ctrl + K # Delete from the cursor to the end of the line. Ctrl + W # Delete the word before the cursor. Ctrl + L # Clear the terminal screen. Ctrl + C # Stop the current process/command. Ctrl + D # Log out or exit the terminal. Ctrl + Z # Pause the current process (can be resumed). Ctrl + R # Search command history (backward search). Up Arrow # Show the previous command (from the command history). Down Arrow # Show the next command (from the command history). !! # Repeat the last command. !n # Repeat the nth command from history. Tab # Auto-complete commands, files, or directories. Tab twice # List all possible completions. Ctrl + Shift + C # Copy the selected text or command. Ctrl + Shift + V # Paste copied text or command. Ctrl + Shift + N # Open a new terminal window. Ctrl + Shift + T # Open a new tab in the terminal. Ctrl + Tab or Ctrl + PageDown # Switch between terminal tabs. ``` *** ## Tools ### vi/[vim](https://www.vim.org/) ```bash vi ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://blog.syselement.com/home/operating-systems/linux/distros/rocky-vm.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.