Add support for reading from stdin and make input handling more robust (

closes #26)

* Adds a `skip_missing` flag
* Adds an `Input` enum to handle different types of inputs

Cargo.toml

@@ -30,6 +30,8 @@ quick-xml = "0.20.0"
 headers = "0.3.2"
 derive_builder = "0.9.0"
 deadpool = "0.6.0"
+shellexpand = "2.0"
+lazy_static = "1.1"
 
 [dependencies.reqwest]
 features = ["gzip"]
@@ -43,3 +45,5 @@ version = "0.2"
 wiremock = "0.3"
 assert_cmd = "1.0"
 predicates = "1.0"
+uuid = { version = "0.8", features = ["v4"] }
+tempfile = "3.1"

README.md

@@ -80,10 +80,32 @@ cargo install lychee
 
 ## Usage
 
-Run it inside a repository with a `README.md`, or specify a file with
+Run it inside a repository with a `README.md`:
 
 ```
-lychee <yourfile>
+lychee
+```
+
+You can also specify various types of inputs:
+
+```
+# check links on a website:
+lychee https://endler.dev/
+
+# check links in a remote file:
+lychee https://raw.githubusercontent.com/lycheeverse/lychee/master/README.md
+
+# check links in local file(s):
+lychee README.md
+lychee test.html info.txt
+
+# check links in local files (by shell glob):
+lychee ~/projects/*/README.md
+
+# check links in local files (lychee supports advanced globbing and ~ expansion):
+lychee "~/projects/big_project/**/README.*"
+# ignore case when globbing, displaying progress and check result for each link:
+lychee --glob-ignore-case --progress --verbose "~/projects/**/[r]eadme.*"
 ```
 
 Optional (to avoid getting rate-limited): set an environment variable with your Github token
@@ -93,7 +115,7 @@ config file.
 ### CLI exit codes
 
 - `0` for success (all links checked successfully or excluded/skipped as configured)
-- `1` for any unexpected runtime failures or config errors
+- `1` for missing inputs and any unexpected runtime failures or config errors
 - `2` for link check failures (if any non-excluded link failed the check)
 
 ## Troubleshooting and workarounds