| Communication | |
| ftp | File transfer protocol |
| login | Sign on to Unix. |
| mailx | Read or send mail. |
| rlogin | Sign on to remote Unix. |
| talk | Write to other terminals. |
| telnet | Connect to another system. |
| vacation | Respond to mail automatically. |
| Comparisons | |
| cmp | Compare two files, byte by byte. |
| comm | Compare items in two sorted files. |
| diff | Compare two files, line by line. |
| diff3 | Compare three files. |
| dircmp | Compare directories. |
| sdiff | Compare two files, side by side. |
| File Management | |
| cat | Concatenate files or display them. |
| cd | Change directory. |
| chmod | Change access modes on files. |
| cp | Copy files. |
| csplit | Break files at specific locations. |
| file | Determines a file's type. |
| head | Show the first few lines of a file. |
| ln | Create filename aliases. |
| ls | List files or directories. |
| mkdir | Create a directory. |
| more | Display files by screenful. |
| mv | Move or rename files or directories. |
| pwd | Print working directory. |
| rcp | Copy files to remote system. |
| rm | Remove files. |
| rmdir | remove directories. |
| split | Split files evenly. |
| tail | Show the last few lines of a file. |
| wc | Count lines, words, and characters. |
| Miscellaneous | |
| banner | Make posters from words. |
| bc | Arbitary precision calculator. |
| cal | Display calendar. |
| calendar | Check for reminders. |
| clear | Clear the screen. |
| man | Get information on a command. |
| nice | Reduce a job's priority. |
| nohup | Preserve a running job after logging out. |
| passwd | Set your login password. |
| script | Produce a transcript of your login session. |
| spell | Report misspelled words. |
| su | Become a superuser. |
| Printing | |
| cancel | Cancel a printer request. |
| lp | Send to the printer. |
| lpstat | Get printer status. |
| pr | Format and paginate for printing. |
| Programming | |
| cb | C source code "beautifier." |
| cc | C compiler. |
| cflow | C function flowchart. |
| ctags | C function references (for vi). |
| ctrace | C debugger using function call tracing. |
| cxref | C cross-references. |
| lint | C program analyzer. |
| ld | Loader. |
| lex | Lexical analyzer generator. |
| make | Execute commands in a specified order. |
| od | Dump input in various formats. |
| strip | Remove data from an object file. |
| truss | Trace signals and system calls. |
| yacc | Parser generator. Can be used with lex. |
| Searching | |
| egrep | Extended version of grep. |
| fgrep | Search files for literal words. |
| find | Search the sysem for filenames. |
| grep | Search files for text patterns. |
| strings | Search binary files of text patterns. |
| Shell Programming | |
| echo | Repeat command-line arguments on the output. |
| expr | Perform arithmetic and comparisons. |
| line | Read a line of input. |
| printf | Format and print command-line arguments. |
| sleep | Pause during processing. |
| test | Test a condition. |
| Storage | |
| compress | Compress files to free up space. |
| cpio | Copy archives in or out. |
| gunzip | Expand compressed (.gz and .z) files (preferred). |
| gzcat | Display contents of compressed files (may be linked to zcat). |
| gzip | Compress files to free up space (preferred). |
| tar | Tape archiver. |
| uncompress | Expand compressed (.z) files. |
| zcat | Display contents of compressed files. |
| System Status | |
| at | Execute commands later. |
| chgrp | Change file group. |
| chown | Change file ownder. |
| crontab | Automate commands. |
| date | Display or set date. |
| df | Show free disk space. |
| du | Show disk usage. |
| env | Show environmental variables. |
| finger | Display information about users. |
| kill | Terminate a running command. |
| ps | Show processes. |
| stty | Set or display terminal settings. |
| who | Show who is logged on. |
| Text Processing | |
| cut | Select columns for display. |
| ex | Line editor underlying vi. |
| fmt | Produce roughly uniform line lengths. |
| join | Merge different columns into a database. |
| nawk | New version of awk (pattern-matching language for textual database files). |
| paste | Merge columns or switch order. |
| sed | Noninteractive text editor. |
| sort | Sort or merge files. |
| tr | Translate (redefine) characters. |
| uniq | Find repeated or unique lines in a file. |
| vi | Visual text editor. |
| xargs | Process many arguments in manageable portions. |
| nroff and troff | |
| deroff | Remove troff codes. |
| eqn | Preprocessor for equations. |
| nroff | Formatter for terminal display. |
| pic | Preprocessor for line graphics. |
| refer | Preprocessor for bibliographic references. |
| tbl | Preprocessor for tables. |
| troff | Formatter for typesetting (including PostScript printers). |
Taken from 'UNIX in a Nutshell', published by O'Reilly, ISBN 1-56592-427-4