# Linux Bash Shell

CS50 IDE is currently using Ubuntu 18 LTS

```bash
$ cat /etc/*release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.3 LTS"
```

## Terminal Shortcuts

| Key/Command | Description                                                                       |
| ----------- | --------------------------------------------------------------------------------- |
| ctrl-a      | Go to the beginning of the line you are currently typing on.                      |
| ctrl-c      | Kill whatever you are running. Also clears everything on current line             |
| ctrl-e      | Go to the end of the line you are currently typing on.                            |
| ctrl-l      | Clear the terminal                                                                |
| ctrl-r      | Reverse search history                                                            |
| ctrl-w      | Delete word on the left                                                           |
| ctrl-y      | Paste                                                                             |
| ctrl-z      | Puts whatever you are running into a suspended background process. fg restores it |
| tab         | auto completion of file or command                                                |
| !!          | repeat last command                                                               |

## Terminal Navigation

| Key/Command        | Description                   |
| ------------------ | ----------------------------- |
| ls -a              | list all files and folders    |
| ls \<foldername>   | list files in folder          |
| ls -lh             | Detailed list, human readable |
| ls -l \*.jpg       | list jpeg files only          |
| ls -lh \<filename> | Result for file only          |
| cd \<foldername>   | change direcxtory             |
| cd /               | goto root directory           |
| cd ..              | go up one folder              |
| pwd                | print working directory       |
| man \<command>     | shows manual                  |

## Pipe

| Key/Command                  | Description                                                                      |
| ---------------------------- | -------------------------------------------------------------------------------- |
| \[command-a] \| \[command-b] | Run command A and then pass the result to command B e.g ps auxwww \| grep google |

## File Manipulation

### tail

| Key/Command         | Description                            |
| ------------------- | -------------------------------------- |
| tail \<filename>    | output the last part of files          |
| tail -f \<filename> | output appended data as the file grows |

### head

| Key/Command         | Description                                       |
| ------------------- | ------------------------------------------------- |
| head \<filename>    | output the first part of files                    |
| head -n \<filename> | print the first NUM lines instead of the first 10 |

### cp

| Key/Command                | Description                     |
| -------------------------- | ------------------------------- |
| cp image.jpg newimage.jpg  | copy and rename a file          |
| cp image.jpg \<foldername> | copy to a folder                |
| cp -R stuff otherstuff     | copy and rename a folder        |
| cp \*.txt stuff            | copy all \*.txt to stuff folder |

### cat

| Key/Command     | Description                                        |
| --------------- | -------------------------------------------------- |
| cat \<filename> | concatenate files and print on the standard output |

### mkdir

| Key/Command         | Description        |
| ------------------- | ------------------ |
| mkdir \<foldername> | create a directory |

### redirect

| Key/Command           | Description                                               |
| --------------------- | --------------------------------------------------------- |
| \[command] > \[file]  | Push output to file, keep in mind it will get overwritten |
| \[command] >> \[file] | Append output to existing file                            |
| \[command] < \[file]  | Tell command to read content from a file                  |

### touch

| Key/Command       | Description            |
| ----------------- | ---------------------- |
| touch \<filename> | change file timestamps |

##


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://www.pythonclassroom.com/python-cloud-options/cloud9/linux-bash-shell.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.