Moving around your system

Early shells allow you to move around your filesystem and run commands, and modern shells like Nu allow you to do the same. Let's take a look at some of the common commands you might use when interacting with your system.

Viewing directory contents

> ls

As we've seen in other chapters, ls is a command for viewing the contents of a path. Nu will return the contents as a table that we can use.

The ls command also takes an optional argument, to change what you'd like to view. For example, we can list the files that end in ".md"

> ls *.md
───┬────────────────────┬──────┬─────────┬────────────
 # │ name               │ type │ size    │ modified 
───┼────────────────────┼──────┼─────────┼────────────
 0  CODE_OF_CONDUCT.md  File   3.4 KB  5 days ago 
 1  CONTRIBUTING.md     File    886 B  5 days ago 
 2  README.md           File  15.0 KB  5 days ago 
 3  TODO.md             File   1.6 KB  5 days ago 
───┴────────────────────┴──────┴─────────┴────────────

Glob patterns (wildcards)

The asterisk (*) in the above optional argument "*.md" is sometimes called a wildcard or a glob. It lets us match anything. You could read the glob "*.md" as "match any filename, so long as it ends with '.md' "

The most general glob is *, which will match all paths. More often, you'll see this pattern used as part of another pattern, for example *.bak and temp*.

In Nushell, we also support double * to talk about traversing deeper paths that are nested inside of other directories. For example, ls **/* will list all the non-hidden paths nested under the current directory.

 ls **/*.md
───┬───────────────────────────────────────────┬──────┬─────────┬───────────
 # │ name                                      │ type │ size    │ modified
───┼───────────────────────────────────────────┼──────┼─────────┼───────────
 0  CODE_OF_CONDUCT.md                         File   3.4 KB  5 days ago
 1  CONTRIBUTING.md                            File    886 B  5 days ago
 2  README.md                                  File  15.0 KB  5 days ago
 3  TODO.md                                    File   1.6 KB  5 days ago
 4  crates/nu-source/README.md                 File   1.7 KB  5 days ago
 5  docker/packaging/README.md                 File   1.5 KB  5 days ago
 6  docs/commands/README.md                    File    929 B  5 days ago
 7  docs/commands/alias.md                     File   1.7 KB  5 days ago
 8  docs/commands/append.md                    File   1.4 KB  5 days ago

Here, we're looking for any file that ends with ".md", and the two asterisks further say "in any directory starting from here".

In other shells (like bash), glob expansion happens in the shell and the invoked program (ls in the example above) receives a list of matched files. In Nushell however, the string you enter is passed "as is" to the command, and some commands (like ls, mv, cp and rm) interpret their input string as a glob pattern. For example the ls command's help pageopen in new window shows that it takes the parameter: pattern: the glob pattern to use (optional).

Globbing syntax in these commands not only supports *, but also matching single characters with ? and character groups with [...]open in new window. Note that this is a more limited syntax than what the dedicated glob Nushell commandopen in new window supports.

Escaping *, ?, [] works by quoting them with single quotes or double quotes. To show the contents of a directory named [slug], use ls "[slug]" or ls '[slug]'. Note that backtick quote doesn't escape glob, for example: cp test dir/* will copy all files inside test dir to current direcroty.

Changing the current directory

> cd new_directory

To change from the current directory to a new one, we use the cd command. Just as in other shells, we can use either the name of the directory, or if we want to go up a directory we can use the .. shortcut.

Changing the current working directory can also be done if cd is omitted and a path by itself is given:

> ./new_directory

Note: changing the directory with cd changes the PWD environment variable. This means that a change of a directory is kept to the current block. Once you exit the block, you'll return to the previous directory. You can learn more about working with this in the environment chapter.

Filesystem commands

Nu also provides some basic filesystem commands that work cross-platform.

We can move an item from one place to another using the mv command:

> mv item location

We can copy an item from one location to another with the cp command:

> cp item location

We can remove an item with the rm command:

> rm item

The three commands also can use the glob capabilities we saw earlier with ls.

Finally, we can create a new directory using the mkdir command:

> mkdir new_directory