fix links and improve travis build test

.travis.yml

@@ -1,5 +1,3 @@
 language: minimal 
-# services:
-#   - docker
 script:
-  - docker run -ti --rm -v $PWD:/mnt:ro dkhamsing/awesome_bot --allow-dupe --allow-redirect --skip-save-results `find . -name "*.md"`
+  - docker run -ti --rm -v $PWD:/mnt:ro dkhamsing/awesome_bot --allow-dupe --allow-redirect --skip-save-results --white-list $(paste -d, -s /mnt/travis_link_check_whitelist.txt) `find . -regex ".*\.\(md\|rst\)$"`

docs/source/reference/commands/unix-and-linux-commands.md

@@ -1894,8 +1894,8 @@ Also config file available
   * [How to download all files (but not HTML) from a website using wget?](https://stackoverflow.com/questions/8755229/how-to-download-all-files-but-not-html-from-a-website-using-wget)
 
   ```bash
-  wget -A pdf,jpg -m -p -E -k -K -np http://site/path/
-  wget --accept pdf,jpg --mirror --page-requisites --adjust-extension --convert-links --backup-converted --no-parent http://site/path/
+  wget -A pdf,jpg -m -p -E -k -K -np <some-url>
+  wget --accept pdf,jpg --mirror --page-requisites --adjust-extension --convert-links --backup-converted --no-parent <some-url>
   ```
 
 * Calculator

travis_link_check_whitelist.txt

@@ -0,0 +1,3 @@
+xlinux.nist.gov
+example.com
+localhost