unix_commands
Table of Contents
Some Basic Unix Commands
Required Reading
Finding Commands
Most user-level commands can be found in the /bin, /usr/bin, and /usr/local/bin directories. Some programs can be found in /sbin and/or /usr/sbin, but those programs are usually reserved for the administrator, and they won't work for you unless you have the password. You can also use the man command to search for commands by keyword, but search is limited. Google is probably a better choice unless you know a specific keyword you're looking for.
A List Of Some Popular Commands
| Command | Description |
|---|---|
arch | Outputs the hardware architecture of the current machine. $ arch x86_64 |
awk | A very powerful text processing program. Entire books have been dedicated to it's use, and I won't even begin to understand everything that it can do. But I'll give you some links. Man PageGNU ManualExamples |
basename | Given a path as a command line argument, output the last segment: $ basename /path/to/directory/file.txt file.txt Additionally, when given a suffix, it will strip off the suffix: $ basename /path/to/directory/file.txt .txt file |
bash | A standard shell program available on almost every Unix-based system. There's a good chance that when you open a terminal this is the shell program that the terminal runs. There are other shell programs, and each has it's own strengths and weaknesses, but for the purposes of these wiki pages the bash script will be what we focus on. Man PageGNU Manual |
basename | Strip directory (and optionally suffix) from path names. Man Page |
bc | An arbitrary-precision command line calculator. Man PageGNU ManualExamples |
cat | Concatenate one or more files. Man Page |
cd | Change directory. Man Page |
chmod | Change file or directory permissions. Man Page Examples |
chown | Change file or directory ownership. Man Page |
clear | Clear the terminal screen. Man Page |
cp | Copy file(s). Man Page Examples |
cut | Read input line at a time, removing a segment of each line before output. Man Page Examples |
date | Return a time and date in configurable formats. Man Page Examples |
df | Return the space used on a filesystem. Man Page Examples |
dirname | Given a path as a command line argument, output everything except the last segment (the inverse of basename). Man Page |
echo | Output a string. Man Page |
exec | Replace the currently running shell or script with a new command. Man Page |
exit | Return an exit code to the parent shell. Man Page |
export | Add a variable to the environment. Man Page |
file | Get information about the type of data inside a file. Man Page |
find | Locate files and/or directories according to user-supplied search criteria. Man Page Examples |
for | A loop command: for <condition>; do <commands>; done |
free | Outputs information about how much memory exists and is being used. Man Page |
grep | Reads input line at a time searching for a regular expression. If found, an action is taken. (Or if not found, an action is taken, depending on command line options used.) Man Page Examples |
gzip | Compress a file. Man Page Examples |
head | Reads input line at a time, outputting the first <N> lines. Man Page Examples |
if | A conditional command: if <condition>; then <commands>; fi Or a more complex example: if <condition>; then <commands> elif <condition2>; then <commands2> ; elif <condition3>; then <commands3> ; ... ; fi |
last | Ouptuts a list of users who last logged into this machine. Man Page |
less | Reads input and prints it to the screen, one page at a time. It pauses the output and gives the user a chance to read what they want. It will resume when the user pressed the space bar or the return key. This command is a newer version of the more command, which does the same thing except without some nice features like the ability to go backward or to search through the file. Man Page Examples |
ln | Creates a symbolic (think Windows' shortcut) or hard link (file physically exists in two places on the filesystem at once). Man Page Examples |
ls | Outputs a directory listing. Man Page Examples |
make | Searched for a file named “Makefile” or “makefile” and, if found, executes the commands within. Execution stops if an error occurs. Man Page GNU Manual |
mc | A text-based file manager. Man Page |
mkdir | Create a directory. Man Page Examples |
mv | Move or rename a file or directory. Man Page Examples |
paste | Merge lines from multiple files. Man Page Examples |
ping | Tests to see if a remote host is reachable over the network. Man Page Examples |
pwd | Ouptuts the current working directory. Man Page |
read | Reads a line from input and stores it in an environment variable. Man Page Examples |
rm | Deletes a file. (NOTE: There is no going back!) Man Page Examples |
rsync | A synchronization tool that can update, copy, or delete files between two locations – both locally and over a network. Man Page Examples |
screen | A fake terminal tool that can be used to run commands even after you log out. Man Page GNU Manual Examples |
script | A fake terminal tool that will store everything typed or printed to the terminal window into a file – handy for recording your terminal session. Man Page |
sed | A search-and-replace text editing tool. Man Page GNU Manual Examples |
set | This command will show you all of the environment variables currently set in your shell. Man Page Examples |
seq | This command takes two integer command line arguments and outputs every integer between them, inclusively, as it counts from the first to the second. Man Page Examples |
shift | Used for processing command line arguments in shell scripts. Man Page Examples |
sort | Reads input one line at a time, sorts the lines, and then outputs the results. Man Page Examples |
ssh | A program for connecting to a remote host securely. Man Page Examples |
tail | Reads input line at a time, only outputting the last <N> lines. Man Page Examples |
tar | A program used to pack multiple files or directories into a single file. Like a zip file, but without compression. (Compression is usually handled by a separate program like gzip, bzip2, or xz.) Man Page Examples |
test | Used to test certain conditional expressions. Often used with if, for, and while conditional statements. Man Page Examples |
time | Used to measure the amount of time that a command takes to execute. Man Page Examples |
touch | Used to create empty files, or to update the timestamp on existing files. Man Page Examples |
tr | Used to transform input. A simple example would be to capitalize text. Man Page Examples |
true | Always returns a successful exit code. Used in conjunction with boolean logic expressions and/or inside if, for, and while conditional statements. Man Page |
uptime | Outputs the amount of time that this machine has been turned on. Man Page |
wc | Reads input line at a time and outputs user-specified metrics such as the number of lines, the number of words, the number of characters, or the number of bytes. Man Page Examples |
wget | A command line tool for interacting with a web server. Can be used to download HTML, or to download a file from a web page. Man Page Examples |
which | Outputs the location of a program, if known. Man Page |
while | A conditional loop command: while <condition>; do <commands>; done |
This list is by no means exhaustive!
unix_commands.txt · Last modified: 2016/05/25 20:22 by peek
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