this is a table of a list of the most commonly used linux command. whenever i forget a command, i look at this list and it helps alot
| alias | Create an alias | |
| awk | Find and Replace text, database sort/validate/index | |
| break | Exit from a loop | |
| builtin | Run a shell builtin | |
| cal | Display a calendar | |
| cse | Conditionally perform a command | |
| cat | Display the contents of a file | |
| cd | Change Directory | |
| cfdisk | Partition table manipulator for Linux | |
| chgrp | Change group ownership | |
| chmod | Change access permissions | |
| chown | Change file owner and group | |
| chroot | Run a command with a different root directory | |
| cksum | Print CRC checksum and byte counts clear Clear terminal screen | |
| cmp | Compare two files | |
| comm | Compare two sorted files line by line | |
| command | Run a command - ignoring shell functions | |
| continue | Resume the next iteration of a loop | |
| cp | Copy one or more files to another location | |
| cron | Daemon to execute scheduled commands | |
| crontab | Schedule a command to run at a later time | |
| csplit | Split a file into context-determined pieces | |
| cut | Divide a file into several parts | |
| date | Display or change the date & time | |
| dc | Desk Calculator | |
| dd | Data Dump - Convert and copy a file | |
| declare | Declare variables and give them attributes | |
| df | Display free disk space | |
| diff | Display the differences between two files | |
| diff3 | Show differences among three files | |
| dir | Briefly list directory contents | |
| dircolors | Colour setup for `ls' | |
| dirname | Convert a full pathname to just a path | |
| dirs | Display list of remembered directories | |
| du | Estimate file space usage | |
| echo | Display message on screen ed A line-oriented text editor (edlin) | |
| egrep | Search file(s) for lines that match an extended expression eject Eject CD-ROM | |
| enable | Enable and disable builtin shell commands | |
| env | Display, set, or remove environment variables | |
| eval | Evaluate several commands/arguments | |
| exec | Execute a command exit Exit the shell | |
| expand | Convert tabs to spaces | |
| export | Set an environment variable | |
| expr | Evaluate expressions | |
| factor | Print prime factors | |
| false | Do nothing, unsuccessfully | |
| fdformat | Low-level format a floppy disk | |
| fdisk | Partition table manipulator for Linux | |
| fgrep | Search file(s) for lines that match a fixed string | |
| find | Search for files that meet a desired criteria | |
| fmt | Reformat paragraph text | |
| fold | Wrap text to fit a specified width. | |
| for | Expand words, and execute commands format Format disks or tapes free Display memory usage | |
| fsck | Filesystem consistency check and repair. | |
| function | Define Function Macros | |
| gawk | Find and Replace text within file(s) | |
| getopts | Parse positional parameters | |
| grep | Search file(s) for lines that match a given pattern | |
| groups | Print group names a user is in | |
| gzip | Compress or decompress named file(s) | |
| hash | Remember the full pathname of a name argument | |
| head | Output the first part of file(s) | |
| history | Command History | |
| hostname | Print or set system name | |
| id | Print user and group id's | |
| if | Conditionally perform a command | |
| import | Capture an X server screen and save the image to file | |
| info | Help info | |
| install | Copy files and set attributes | |
| join | Join lines on a common field | |
| kill | Stop a process from running | |
| less | Display output one screen at a time | |
| let | Perform arithmetic on shell variables | |
| ln | Make links between files | |
| local | Create variables | |
| locate | Find files | |
| logname | Print current login name | |
| logout | Exit a login shell | |
| lpc | Line printer control program | |
| lpr | Off line print lprint Print a file lprintd Abort a print job lprintq List the print queue | |
| lprm | Remove jobs from the print queue | |
| ls | List information about file(s) | |
| m4 | Macro processor | |
| man | Help manual | |
| mkdir | Create new folder(s) | |
| mkfifo | Make FIFOs (named pipes) | |
| mknod | Make block or character special files | |
| more | Display output one screen at a time | |
| mount | Mount a file system | |
| mtools | Manipulate MS-DOS files | |
| mv | Move or rename files or directories | |
| nice | Set the priority of a command or job | |
| nl | Number lines and write files | |
| nohup | Run a command immune to hangups | |
| passwd | Modify a user password | |
| paste | Merge lines of files pathchk Check file name portability | |
| popd | Restore the previous value of the current directory | |
| pr | Convert text files for printing printcap Printer capability database printenv Print environment variables | |
| printf | Format and print data | |
| ps | Process status | |
| pushd | Save and then change the current directory | |
| pwd | Print Working Directory | |
| quota | Display disk usage and limits | |
| quotacheck | Scan a file system for disk usage | |
| quotactl | Set disk quotas | |
| ram | ram disk device | |
| rcp | Copy files between two machines. | |
| read | read a line from standard input | |
| readonly | Mark variables/functions as readonly remsync Synchronize remote files via email | |
| return | Exit a shell function | |
| rm | Remove files | |
| rmdir | Remove folder(s) | |
| rpm | Remote Package Manager | |
| rsync | Remote file copy (Synchronize file trees) screen Terminal window manager | |
| sdiff | Merge two files interactively | |
| sed | Stream Editor | |
| select | Accept keyboard input | |
| seq | Print numeric sequences | |
| set | Manipulate shell variables and functions | |
| shift | Shift positional parameters | |
| shopt | Shell Options | |
| shutdown | Shutdown or restart linux | |
| sleep | Delay for a specified time | |
| sort | Sort text files | |
| source | Run commands from a file `.' | |
| split | Split a file into fixed-size pieces | |
| su | Substitute user identity | |
| sum | Print a checksum for a file | |
| symlink | Make a new name for a file | |
| sync | Synchronize data on disk with memory | |
| tac | Concatenate and write files in reverse | |
| tail | Output the last part of files | |
| tar | Tape ARchiver | |
| tee | Redirect output to multiple files | |
| test | Evaluate a conditional expression | |
| time | Measure Program Resource Use | |
| times | User and system times | |
| touch | Change file timestamps | |
| top | List processes running on the system | |
| traceroute | Trace Route to Host trap Run a command when a signal is set(bourne) | |
| tr | Translate, squeeze, and/or delete characters | |
| true | Do nothing, successfully | |
| tsort | Topological sort | |
| tty | Print filename of terminal on stdin | |
| type | Describe a command | |
| ulimit | Limit user resources | |
| umask | Users file creation mask umount Unmount a device | |
| unalias | Remove an alias | |
| uname | Print system information | |
| unexpand | Convert spaces to tabs | |
| uniq | Uniquify files | |
| units | Convert units from one scale to another | |
| unset | Remove variable or function names | |
| unshar | Unpack shell archive scripts | |
| until | Execute commands (until error) | |
| useradd | Create new user account | |
| usermod | Modify user account | |
| users | List users currently logged in | |
| uuencode | Encode a binary file | |
| uudecode | Decode a file created by uuencode v Verbosely list directory contents (`ls -l -b') vdir Verbosely list directory contents (`ls -l -b') | |
| watch | Execute/display a program periodically | |
| wc | Print byte, word, and line counts | |
| whereis | Report all known instances of a command | |
| which | Locate a program file in the user's path. | |
| while | Execute commands | |
| who | Print all usernames currently logged in whoami Print the current user id and name (`id -un') | |
| xargs | Execute utility, passing constructed argument list(s) | |
| yes | Print a string until interrupted | |
| .period | Run commands from a file | |
| ### | Comment / Remark | |