Created SC2057 (markdown)

SC2057.md

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+## Unknown binary operator.
+
+### Problematic code:
+
+```sh
+[ "$var" -leq 42 ]
+```
+
+### Correct code:
+
+```sh
+[ "$var" -le 42 ]
+```
+
+### Rationale:
+
+You are using an unknown binary operator in a `test` expression. In bash, use `help test` to see a list of supported operators:
+
+      FILE1 -nt FILE2  True if file1 is newer than file2 (according to
+                       modification date).
+
+      FILE1 -ot FILE2  True if file1 is older than file2.
+
+      FILE1 -ef FILE2  True if file1 is a hard link to file2.
+
+      STRING1 = STRING2
+                     True if the strings are equal.
+      STRING1 != STRING2
+                     True if the strings are not equal.
+      STRING1 < STRING2
+                     True if STRING1 sorts before STRING2 lexicographically.
+      STRING1 > STRING2
+                     True if STRING1 sorts after STRING2 lexicographically.
+
+      arg1 OP arg2   Arithmetic tests.  OP is one of -eq, -ne,
+                     -lt, -le, -gt, or -ge.
+
+    Arithmetic binary operators return true if ARG1 is equal, not-equal,
+    less-than, less-than-or-equal, greater-than, or greater-than-or-equal
+    than ARG2.
+
+The operators 
+
+
+### Exceptions:
+
+None. If you've tested and verified that the operator works, please [submit a bug report](https://github.com/koalaman/shellcheck/issues).
+
+### Related resources:
+
+* [The classic test command](http://wiki.bash-hackers.org/commands/classictest) on the Bash Hackers wiki.
+* [The conditional expression](http://wiki.bash-hackers.org/syntax/ccmd/conditional_expression) on the Bash Hackers wiki.
+* [Tests and conditionals](https://mywiki.wooledge.org/BashGuide/TestsAndConditionals) on the Wooledge BashGuide.