File Operations Using CLI

Now we know how to navigate around our system, let’s interact with some files:

Normally is good to have filenames with extension, but sometime that is not the case on linux/Unix/Unix-like systems,

To figure out what type of file it is:

file <filename>

to copy some files:

cp [options] <source files> <destination>

it support wildcards for file names, such as:

# this will copy every file with name starts with "image"
# and extension of ".jpg" to the Downloads folder
cp image*.jpg ~/Downloads

to prompt you when copying over existing files, use -i the interative option, I recommend adding it when copying multiple files
```
cp -i ./old-workspace/* ./new-workspace/
```
to forcefully overwrite existing files
```
cp -f ./patch-files/* ./broken-mess/
```
to create backups of source files
```
cp -fb ./updates/* ./old-build/
```
to copy multiple files, and files of subdirectories
```
cp -r ./notes/ /mnt/backupdisk/
```

The mv command has similar parameter to cp command:

mv [options] <source files> <destination>

In linux/unix/unix-like systems, mv is also used for renaming files

mv <orginal_filename> <new_filename>

To make a new directory:

mkdir <new directory pathname>

if you are creating a subdirectory of a directory that doesn’t exist yet, use the -p parents flag to create them automatically
```
mkdir -p ~/fridge/drinks/
```

Similarily, to remove a directory

rmdir <directory pathname>

Note: directory should be empty, else is better to use the rm -r command

To concatenate file (think of it as grabing the contents of the file for now), and print to standard output (will explain standard I/O stream later)

cat [options] <filenames>

alternative to cat:

bat https://github.com/sharkdp/bat written in Rust
A cat(1) clone with syntax highlighting and Git integration.

the opposite of cat is tac, which will function the same but reversed, print from the end to the beginning

sometime cating a file is not a good option, files such as logs are way too long, another option would be

less system.log

less is more, which is ironic, because less shows file line by line that you can scroll through.

more errors.log

but the more command will show by pages(how ever many can fit on screen at once)

These are less useful, but still good to know.

To show the beginning of a file (default 10 lines):

head doc.md

to specify exactly how many lines to show, use the lines option
```
head -n 3 letter.txt
```

The opposite command is tail, which shows the last part of a file (default 10 lines):

tail recipt.txt

to follow the file as it grows with new contents added
```
tail -f activities.log
```