| apropos | Search Help manual pages (man -k) |
| apt-get | Search for and install software packages (Debian) |
| aptitude | Search for and install software packages (Debian) |
| aspell | Spell Checker |
| awk | Find and Replace text, database sort/validate/index |
| basename | Strip directory and suffix from filenames |
| bash | GNU Bourne-Again Shell |
| bc | Arbitrary precision calculator language |
| bg | Send to background |
| break | Exit from a loop |
| builtin | Run a shell builtin |
| bzip2 | Compress or decompress named files |
| cal | Display a calendar |
| case | Conditionally perform a command |
| cat | Concatenate and print (display) the content of files |
| cd | Change Directory |
| cfdisk | Partition table manipulator for Linux |
| chgrp | Change group ownership |
| chkconfig | System services (runlevel) |
| 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 and time |
| dc | Desk Calculator |
| dd | Convert and copy a file, write disk headers, boot records |
| ddrescue | Data recovery tool |
| 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 |
| dig | DNS lookup |
| 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 |
| dmesg | Print kernel & driver messages |
| du | Estimate file space usage |
| echo | Display message on screen |
| egrep | Search files for lines that match an extended expression |
