Add no hard link support for ln

README.md

@@ -178,6 +178,7 @@ using the matched rule and runs it. Rules enabled by default are as follows:
 * `java` – removes `.java` extension when running Java programs;
 * `javac` – appends missing `.java` when compiling Java files;
 * `lein_not_task` – fixes wrong `lein` tasks like `lein rpl`;
+* `ln_no_hard_link` – catches hard link creation on directories, suggest symbolic link;
 * `ls_lah` – adds `-lah` to `ls`;
 * `man` – changes manual section;
 * `man_no_space` – fixes man commands without spaces, for example `mandiff`;

tests/rules/test_ln_no_hard_link.py

@@ -0,0 +1,45 @@
+from thefuck.rules.ln_no_hard_link import match, get_new_command
+from tests.utils import Command
+
+
+def test_match():
+    err = "hard link not allowed for directory"
+    assert not match(Command())
+
+    cmd1 = Command("ln barDir barLink", stderr="ln: ‘barDir’: {}".format(err))
+    assert match(cmd1)
+
+    cmd2 = Command("sudo ln a b", stderr="ln: ‘a’: {}".format(err))
+    assert match(cmd2)
+
+    cmd3 = Command("ln a b", stderr="... hard link")
+    assert not match(cmd3)
+
+    cmd4 = Command("sudo ln a b", stderr="... hard link")
+    assert not match(cmd4)
+
+    cmd5 = Command("a b", stderr=err)
+    assert not match(cmd5)
+
+    cmd6 = Command("sudo ln -nbi a b", stderr="ln: ‘a’: {}".format(err))
+    assert match(cmd6)
+
+
+def test_get_new_command():
+    cmd1 = Command("ln barDir barLink")
+    assert get_new_command(cmd1) == "ln -s barDir barLink"
+
+    cmd2 = Command("sudo ln barDir barLink")
+    assert get_new_command(cmd2) == "sudo ln -s barDir barLink"
+
+    cmd3 = Command("sudo ln -nbi a b")
+    assert get_new_command(cmd3) == "sudo ln -s -nbi a b"
+
+    cmd4 = Command("ln -nbi a b && ls")
+    assert get_new_command(cmd4) == "ln -s -nbi a b && ls"
+
+    cmd5 = Command("ln a ln")
+    assert get_new_command(cmd5) == "ln -s a ln"
+
+    cmd6 = Command("sudo ln a ln")
+    assert get_new_command(cmd6) == "sudo ln -s a ln"

thefuck/rules/ln_no_hard_link.py

@@ -0,0 +1,24 @@
+"""Suggest creating symbolic link if hard link is not allowed.
+
+Example:
+> ln barDir barLink
+ln: ‘barDir’: hard link not allowed for directory
+
+--> ln -s barDir barLink
+"""
+
+import re
+from thefuck.utils import for_app
+from thefuck.specific.sudo import sudo_support
+
+
+@sudo_support
+@for_app('ln')
+def match(command):
+    return (command.stderr.endswith("hard link not allowed for directory") and
+            command.script.startswith("ln "))
+
+
+@sudo_support
+def get_new_command(command):
+    return re.sub(r'^ln ', 'ln -s ', command.script)