Add the file subcommand.

source/cli/mod.rs

@@ -3,6 +3,7 @@
 pub use {
   crate::cli::run::run,
   clap::{Parser, Subcommand},
+  std::path::PathBuf,
 };
 
 mod run;
@@ -26,6 +27,13 @@ pub enum MainSubcommand {
     command: ArgumentsSubcommand,
   },
 
+  /// The file subcommand.
+  File {
+    /// The file subcommands.
+    #[command(subcommand)]
+    command: FileSubcommand,
+  },
+
   /// The log subcommand.
   Log {
     /// The data to log.
@@ -52,3 +60,15 @@ pub enum ArgumentsSubcommand {
     newline: bool,
   },
 }
+
+/// The file subcommands
+#[derive(Debug, Subcommand)]
+pub enum FileSubcommand {
+  /// Check whether a file exists, if the file does not exist the exit code will
+  /// be 1.
+  Exists {
+    /// The path to a potential file.
+    #[arg()]
+    file: PathBuf,
+  },
+}

source/cli/run.rs

@@ -2,7 +2,9 @@
 
 use {
   crate::{
-    cli::{ArgumentsSubcommand, Cli, MainSubcommand::*, Parser},
+    cli::{
+      ArgumentsSubcommand, Cli, FileSubcommand, MainSubcommand::*, Parser,
+    },
     logging::append_line_to_file,
   },
   chrono::{SecondsFormat, Utc},
@@ -26,6 +28,16 @@ pub fn run() {
       }
     },
 
+    File {
+      command: file_subcommand,
+    } => match file_subcommand {
+      FileSubcommand::Exists { file } => {
+        if !file.exists() {
+          std::process::exit(1);
+        }
+      }
+    },
+
     Log { data_to_log, file } => {
       let log_line = format!(
         "{} {}",