resolve #2860 add support for multiline command

AUTHORS.txt

@@ -309,3 +309,4 @@ Contributors:
 - Patrick Scheibe <patrick@halirutan.de>
 - Kyle Brown <kylebrown9@github>
 - Marcus Ortiz <mportiz08@gmail.com>
+- Guillaume Grossetie <ggrossetie@yuzutech.fr>

CHANGES.md

@@ -12,6 +12,7 @@ New Languages:
 
 Language Improvements:
 
+- enh(shell) Add support for multiline commands with line continuation `\` (#2861) [Guillaume Grossetie][]
 - bug(xml) XML grammar was far too imprecise/fuzzy [Josh Goebel][]
 - enh(xml) Improve precision to prevent false auto-detect positives [Josh Goebel][]
 - fix(js/ts) Prevent for/while/if/switch from falsly matching as functions (#2803) [Josh Goebel][]
@@ -58,6 +59,7 @@ New themes:
 [Patrick Scheibe]: https://github.com/halirutan
 [Kyle Brown]: https://github.com/kylebrown9
 [Marcus Ortiz]: https://github.com/mportiz08
+[Guillaume Grossetie]: https://github.com/mogztter
 
 
 ## Version 10.3.1

src/languages/shell.js

@@ -14,7 +14,7 @@ export default function(hljs) {
         className: 'meta',
         begin: '^\\s{0,3}[/\\w\\d\\[\\]()@-]*[>%$#]',
         starts: {
-          end: '$', subLanguage: 'bash'
+          end: '[^\\\\]\\s*$', subLanguage: 'bash'
         }
       }
     ]

test/markup/shell/command-continuation.expect.txt

@@ -0,0 +1,10 @@
+<span class="hljs-meta">$</span><span class="bash"> docker run \
+      --publish=7474:7474 --publish=7687:7687 \
+      --volume=/neo4j/data:/data \
+      --volume=/neo4j/plugins:/plugins \
+      --volume=/neo4j/conf:/conf \
+      --volume=/logs/neo4j:/logs \
+      --user=<span class="hljs-string">&quot;<span class="hljs-subst">$(id -u neo4j)</span>:<span class="hljs-subst">$(id -g neo4j)</span>&quot;</span> \
+      --group-add=<span class="hljs-variable">$groups</span> \
+      neo4j:3.4
+</span>

test/markup/shell/command-continuation.txt

@@ -0,0 +1,9 @@
+$ docker run \
+      --publish=7474:7474 --publish=7687:7687 \
+      --volume=/neo4j/data:/data \
+      --volume=/neo4j/plugins:/plugins \
+      --volume=/neo4j/conf:/conf \
+      --volume=/logs/neo4j:/logs \
+      --user="$(id -u neo4j):$(id -g neo4j)" \
+      --group-add=$groups \
+      neo4j:3.4

test/markup/shell/plain-prompt.expect.txt

@@ -1,2 +1,3 @@
 <span class="hljs-meta">&gt;</span><span class="bash"> foo</span>
-<span class="hljs-meta">&gt;</span><span class="bash"> /bin/sh</span>
+<span class="hljs-meta">&gt;</span><span class="bash"> /bin/sh
+</span>