Document fs CLI command (nextflow-io#4328)

Signed-off-by: Ben Sherman <[email protected]>

docs/cli.md

@@ -550,6 +550,66 @@ Forcefully drop the `nextflow-io/hello` pipeline, ignoring any local changes.
 $ nextflow drop nextflow-io/hello -f
 ```
 
+### fs
+
+Perform basic filesystem operations.
+
+**Usage**
+
+```console
+$ nextflow fs [subcommands]
+```
+
+**Description**
+
+The `fs` command is used to perform filesystem operations like copy, move, delete, list directory, etc. Like the `file()` method, it can work with local files, remote URLs, and remote object storage. Storage credentials can be provided through the same manner as launching a pipeline (Nextflow config, environment vars, etc).
+
+**Options**
+
+`-h, -help`
+: Print the command usage.
+
+**Examples**
+
+List a directory.
+
+```console
+$ nextflow fs list <directory>
+```
+
+Print the contents of a file to standard output.
+
+```console
+$ nextflow fs cat <file>
+```
+
+Copy a file or directory.
+
+```console
+$ nextflow fs cp <source> <target>
+```
+
+Move a file or directory.
+
+```console
+$ nextflow fs mv <source> <target>
+```
+
+Delete a file or directory.
+
+```console
+$ nextflow fs rm <path>
+```
+
+:::{versionadded} 23.10.0
+:::
+
+Print file or directory attributes.
+
+```console
+$ nextflow fs stat <path>
+```
+
 ### help
 
 Print the top-level help or specific help for a command.

modules/nextflow/src/main/groovy/nextflow/cli/CmdFs.groovy

@@ -234,7 +234,7 @@ class CmdFs extends CmdBase implements UsageAware {
     private void run0() {
         final cmd = findCmd(args[0])
         if( !cmd ) {
-            throw new AbortOperationException("Unknown file system command: `$cmd`")
+            throw new AbortOperationException("Unknown fs sub-command: `$cmd`")
         }
 
         Path target
@@ -311,7 +311,7 @@ class CmdFs extends CmdBase implements UsageAware {
             if( sub )
                 println sub.usage()
             else {
-                throw new AbortOperationException("Unknown cloud sub-command: ${args[0]}")
+                throw new AbortOperationException("Unknown fs sub-command: ${args[0]}")
             }
         }