diff --git a/crates/pacdef_core/src/core.rs b/crates/pacdef_core/src/core.rs
index cf2d02a..9b04d19 100644
--- a/crates/pacdef_core/src/core.rs
+++ b/crates/pacdef_core/src/core.rs
@@ -207,7 +207,7 @@ impl Pacdef {
 
     fn show_group_content(&self, groups: &ArgMatches) -> Result<()> {
         let mut iter = groups
-            .get_many::<String>("group")
+            .get_many::<String>("groups")
             .context("getting groups from args")?
             .peekable();
 
@@ -218,7 +218,7 @@ impl Pacdef {
                 .groups
                 .iter()
                 .find(|g| g.name == *arg_group)
-                .ok_or_else(|| anyhow!("group {} not found", *arg_group))?;
+                .ok_or_else(|| anyhow!(crate::Error::GroupFileNotFound(g.name)))?;
 
             if show_more_than_one_group {
                 let name = &group.name;
@@ -297,7 +297,13 @@ impl Pacdef {
             .collect();
 
         for file in &paths {
-            ensure!(!file.exists(), "group already exists under {file:?}");
+            file.file_name()
+                .ok_or_else(|| crate::Error::InvalidGroupName("..".to_string()))?;
+
+            ensure!(
+                !file.exists(),
+                crate::Error::GroupAlreadyExists(file.clone())
+            );
         }
 
         for file in &paths {
diff --git a/crates/pacdef_core/src/errors.rs b/crates/pacdef_core/src/errors.rs
index 880ffcf..510903c 100644
--- a/crates/pacdef_core/src/errors.rs
+++ b/crates/pacdef_core/src/errors.rs
@@ -1,5 +1,6 @@
 use std::error::Error as ErrorTrait;
 use std::fmt::Display;
+use std::path::PathBuf;
 
 /// Error types for pacdef.
 #[derive(Debug)]
@@ -11,6 +12,10 @@ pub enum Error {
     ConfigFileNotFound,
     /// Group file not found.
     GroupFileNotFound(String),
+    /// Group already exists.
+    GroupAlreadyExists(PathBuf),
+    /// Invalid group name ('.' or '..')
+    InvalidGroupName(String),
 }
 
 impl Display for Error {
@@ -19,6 +24,13 @@ impl Display for Error {
             Self::NoPackagesFound => f.write_str("no packages matching query"),
             Self::ConfigFileNotFound => f.write_str("config file not found"),
             Self::GroupFileNotFound(name) => f.write_str(&format!("group file '{name}' not found")),
+            Self::GroupAlreadyExists(path) => f.write_str(&format!(
+                "group file '{}' already exists",
+                path.to_string_lossy()
+            )),
+            Self::InvalidGroupName(name) => {
+                f.write_str(&format!("group name '{name}' is not valid"))
+            }
         }
     }
 }