Improve installer updates and dependency checks and add command aliases

README.md

@@ -46,9 +46,34 @@ The script detects your OS and architecture, downloads the matching binary from
 To install to a custom directory:
 
 ```sh
-INSTALL_DIR=~/.local/bin curl -fsSL https://git.zb-server.de/Sebi/ssh-netbox-wrapper/raw/branch/main/install.sh | bash
+curl -fsSL https://git.zb-server.de/Sebi/ssh-netbox-wrapper/raw/branch/main/install.sh | INSTALL_DIR="$HOME/.local/bin" bash
 ```
 
+### Updating an existing installation
+
+Run the same one-liner again to update to the latest release. The installer uses
+an existing `netssh` found in `PATH`, or `/usr/local/bin/netssh` for a new installation.
+`INSTALL_DIR` explicitly overrides the destination. The replacement is atomic,
+so an installed binary can be updated while it is running.
+
+The installer checks all required programs before downloading or modifying files:
+`curl`, `uname`, `sed`, `awk`, `mktemp`, `rm`, `dirname`, `readlink`, `mkdir`, `cat`,
+`install`, `mv`, `cp`, `chmod`, `cmp`, and either `sha256sum` (Linux) or `shasum`
+(macOS). Bash runs the installer; `sudo` is checked beforehand only if the target
+directory requires elevated permissions. Missing programs are listed together;
+install them with your package manager and retry. **Python is not required. SHA-256 verification is mandatory:** missing,
+duplicate or mismatched checksums abort the update before replacing anything.
+
+It also consolidates netssh integration in existing Bash, Zsh and Fish profiles
+and creates the current shell's rc file when needed. Old standalone netssh hooks,
+inline host aliases and `eval "$(netssh alias)"` entries are replaced by a single
+managed block per rc file. Legacy entries in login profiles are removed as well.
+Other shell settings, NetBox configuration, cache and local notes are preserved.
+Every changed existing profile gets a `.netssh-backup.XXXXXX` backup; symlinks
+and permissions are preserved. `XDG_CONFIG_HOME`, `XDG_CACHE_HOME` and `ZDOTDIR`
+are respected. Alias files and installed shell completions are regenerated.
+Open a **new terminal** after updating to load the new aliases and hooks.
+
 ### Build from source
 
 ```sh
@@ -68,7 +93,7 @@ Re-run it at any time to change settings without editing the file manually:
 netssh configure
 ```
 
-The wizard walks through NetBox connection, SSH defaults, resolver strategies, and cache TTL,
+The wizard walks through NetBox connection, SSH defaults, resolver strategies, cache TTL, and an optional command alias,
 then saves to `~/.config/netssh.yaml`.
 
 ### Manual config
@@ -109,6 +134,31 @@ shortcuts:
 
 Any value can be overridden with environment variables (`NETSSH_NETBOX_URL`, `NETSSH_NETBOX_TOKEN`, etc.).
 
+### Short command alias
+
+In `netssh configure`, set **Command alias** to `j` to use `j` anywhere you would
+use `netssh`:
+
+```sh
+j                    # interactive server search
+j server01           # connect to a server
+j notes show server01
+```
+
+The setting is saved as:
+
+```yaml
+shell:
+  alias: j
+```
+
+The wizard regenerates shell aliases and installs the current shell's hook when
+an alias is set. Open a new terminal (or follow the displayed reload command).
+Changing the setting replaces the old generated alias; leaving it empty disables
+it for new shells. The command alias takes priority over a host alias with the
+same name and works even when no servers are cached. Environment override:
+`NETSSH_SHELL_ALIAS=j`.
+
 ### API tokens
 
 NetBox supports two token formats:
@@ -457,7 +507,7 @@ Both are non-blocking — the refresh runs as a background process and never del
 ## Development
 
 ```sh
-go test ./...        # run all tests
+go test ./...        # includes offline installer/update tests
 go build ./...       # build all packages
 ```