1. Common Linux Commands and Their Meanings pwd: print work directory, prints the current directory and displays the absolute path of the current working directory. ps: process status, similar to the Windows Task Manager, commonly used parameters -auxf, ps -auxf are used to display process status. df: disk free, displays information about available disk space and inode information, reporting the remaining free space of installed devices or directories. du: Disk usage. rpm: RedHat Package Management, the package management tool for RedHat. rmdir: Remove Directory, deletes a directory. rm: Remove, deletes a directory or file. cat: concatenate, combines the contents of files, e.g., cat file1 file2>>file3 can combine the contents of file 1 and file 2 into file 3. insmod: install module, loads a module. ln -s: link -soft, creates a soft link (shortcut). mkdir: Make Directory, creates a directory. touch: touch (creates an empty file or changes the file timestamp). man: Manual, view command manuals. su: Switch user, switches users. cd: Change directory, changes the directory. ls: List files, lists files. mkfs: Make file system, creates a file system. fsck: File system check, checks the file system. uname: Unix name, displays system information. lsmod: List modules, lists loaded modules. mv: Move file, moves a file. cp: Copy file, copies a file. ln: Link files, links files. fg: Foreground, brings a background process to the foreground. bg: Background, sends a foreground process to the background. chown: Change owner, changes the file owner. chgrp: Change group, changes the file group. chmod: Change mode, changes file permissions. umount: Unmount, unmounts a file system. dd: Convert and copy (named “dd” because “cc” already represents C Compiler), used for converting and copying data, such as disk dumps. tar: Tape archive, used for packaging and compressing files. ldd: List dynamic dependencies, lists dynamic dependencies. rmmod: Remove module, removes a module.2. File Extension Meanings.a: Archive, static library. .so: Shared object, dynamically linked library. .o: Object file, the result of compiling C/C++ source files. 3. Package ManagersRPM: Red Hat Package Manager, the package management tool for Red Hat distributions. dpkg: Debian Package Manager, the package management tool for Debian distributions. apt: Advanced Package Tool, an advanced package management tool in Debian or Debian-based distributions. 4. Other Linux Command Abbreviations and Meaningsbin: Binaries, binary files. /dev: Devices, devices. /etc: Etcetera, stores system configuration files, etc. /lib: LIBrary, stores system library files. /proc: Processes, stores runtime process information. /sbin: Superuser Binaries, binaries for superusers. /tmp: Temporary, temporary file directory. /usr: Unix Shared Resources, stores shared resources. /var: Variable, stores variable data, such as logs. FIFO: First In, First Out. GRUB: GRand Unified Bootloader, boot loader. IFS: Internal Field Separators, internal field separators. LILO: LInux LOader, Linux boot loader (older). SQL: Structured Query Language. PHP: Personal Home Page Tools or PHP Hypertext Preprocessor. PS: Prompt String or Processes Status. Perl: “Practical Extraction and Report Language” or “Pathologically Eclectic Rubbish Lister”. Tcl: Tool Command Language. Tk: ToolKit, the graphical toolkit for Tcl. VT: Video Terminal. YaST: Yet Another Setup Tool, a tool for system configuration. apache: “a patchy” server, an open-source web server software. ar: archiver, archiver. as: assembler, assembler. awk: derived from the initials of “Aho, Weinberger, and Kernighan”, a text processing tool. bash: Bourne Again SHell, the shell of the GNU project. bc: Basic (Better) Calculator. biff: named after a dog owned by author Heidi Stettner at U.C. Berkeley that barked at the mailman, a mail notification program. cal: Calendar, calendar command. cmp: compare, compares file contents. cobra: Common Object Request Broker Architecture. comm: common, compares the common lines of two ordered files. cpio: CoPy In and Out, used for file backup and recovery. cpp: C Pre Processor. cron: Chronos (Greek for time), used for scheduled tasks. cups: Common Unix Printing System. cvs: Current Version System, version control system. daemon: Disk And Execution MONitor, a daemon process. dc: Desk Calculator. diff: Difference, compares file differences. dmesg: diagnostic message, displays messages from the kernel ring buffer. ed: editor, text editor. egrep: Extended GREP. elf: Extensible Linking Format. elm: ELectronic Mail, email program. emacs: Editor MACroS, text editor. eval: EVALuate. ex: EXtended, extended mode of the vi editor. exec: EXECute, executes commands. fd: file descriptors. fgrep: Fixed GREP. fmt: format, formats text. fstab: File System TABle. fvwm: F*** Virtual Window Manager. gawk: GNU AWK. gpg: GNU Privacy Guard, used for encryption and signing. groff: GNU troff, typesetting system. hal: Hardware Abstraction Layer. joe: Joe’s Own Editor, text editor. ksh: Korn SHell, a Unix shell. lame: Lame Ain’t an MP3 Encoder. lex: LEXical analyser. lisp: LISt Processing or Lots of Irritating Superfluous Parentheses. lpr: Line PRint. lsof: LiSt Open Files. m4: Macro processor Version 4. mawk: Mike Brennan’s AWK. mc: Midnight Commander, file manager. mknod: Make Node, creates device nodes. motd: Message of The Day. mozilla: MOsaic GodZILLa, a web browser. mtab: Mount TABle. nano: Nano’s ANOther editor. nawk: New AWK. nl: Number of Lines. nm: names, lists symbols in object files. nohup: No HangUP, allows commands to run in the background without being hung up. nroff: New ROFF. od: Octal Dump. passwd: Passwd, changes user password. pg: pager, paginates output. pico: PIne’s message COmposition editor. pine: “Program for Internet News & Email” or “Pine is not Elm”. ping: Packet Internet Grouper, used to test network connectivity. printcap: PRINTer CAPability. popd: POP Directory. pr: pre, formats print files. pty: pseudo tty. pushd: PUSH Directory. rc: runcom or run command. rev: REVerse. rn: Read News. roff: RunOFF. rsh, rlogin, rvim: r: Remote. rxvt: ouR XVT, a terminal emulator. sed: Stream Editor. seq: SEQuence. shar: Shell ARchive. slrn: S-Lang rn. ssh: Secure Shell, used for remote login and file transfer. ssl: Secure Sockets Layer, used for network communication encryption. stty: Set TTY. svn: SubVersion. tcsh: TENEX C shell. tee: T (T-shaped pipe interface). telnet: TEminaL over Network. termcap: terminal capability. terminfo: terminal information. tex: τέχνη (Greek for art). tr: translate. troff: Typesetter new ROFF. tsort: Topological SORT. tty: TeleTypewriter. twm: Tom’s Window Manager. tz: TimeZone. udev: Userspace DEV. ulimit: User’s LIMIT. umask: User’s MASK. uniq: UNIQue. vi: VIsual or Very Inconvenient. vim: Vi IMproved. wall: write all. wc: Word Count. wine: WINE Is Not an Emulator. xargs: eXtended ARGuments. xdm: X Display Manager. xlfd: X Logical Font Description. xmms: X Multimedia System. xrdb: X Resources DataBase. xwd: X Window Dump. yacc: yet another compiler compiler. Fish: the Friendly Interactive SHell. MIME: Multipurpose Internet Mail Extensions. ECMA: European Computer Manufacturers Association.