Basic Linux commands

‼️ To begin make sure you have a user account at CSC that is a member of a project which has access to the Puhti service.

☝🏻 You should also have already logged in to Puhti with SSH or via the Puhti web interface (and opened a login node shell).

Navigating folders

Now that you have logged in to Puhti, check which folder you are in by typing pwd and hitting Enter:
```
pwd
```
Check if there are any files:
```
ls
```

Make a directory and see if it appears:

mkdir YourNameTestFolder    # replace YourName
ls

Go to that folder.

cd YourNameTestFolder       # replace YourName

💡 Note: if you just type cd and the first letter of the folder name, then hit tab key, the terminal completes the name. Handy!

Exploring files

Download a file into this new folder. Use the command wget for downloading from a URL:

wget https://raw.githubusercontent.com/csc-training/csc-env-eff/master/part-1/prerequisites/my-first-file.txt

Check what kind of file you got and what size it is using the ls command with some extra options:

ls -lth         # options are l for long format, t for sorting by time and h for convenient size units. Anything that starts with a hashtag is a comment and is not executed

Use the less command to check out what the file looks like:
```
less my-first-file.txt
```
To exit the less preview of the file, hit q.

💡 Tip: Instead of less you can use cat which prints the content of the file(s) straight into the command line. For long texts less is recommended.

Make a copy of this file:

cp my-first-file.txt YourName-first-file.txt    # replace YourName
ls -lth
less YourName-first-file.txt                    # replace YourName

Remove the file we originally downloaded (leave your own copy).
```
rm my-first-file.txt
ls
```

💡 Tip: If you don’t want to have duplicate files you can use mv to ‘move/rename’ the file. Syntax is the same: mv /path/to/source/oldname /path/to/destination/newname.

More information

Learn how to edit that file in the next tutorial!

💡 For more information of a given command line command: type man command or command --help where command is replaced with the one that you need help with.

💡 Tip: If you remember a part of a command that you have used recently you can search for it with the command history | grep string. This will show all your used commands that have included the string string (replace this with the pattern you are searching for).