[Docs] `unalias`: add more specific error message for builtin aliases
diff --git a/nvm.sh b/nvm.sh
index 5581998..f2744c6 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -3335,6 +3335,18 @@
nvm_err 'Aliases in subdirectories are not supported.'
return 1
fi
+
+ local NVM_IOJS_PREFIX
+ local NVM_NODE_PREFIX
+ NVM_IOJS_PREFIX="$(nvm_iojs_prefix)"
+ NVM_NODE_PREFIX="$(nvm_node_prefix)"
+ case "$1" in
+ "stable" | "unstable" | "${NVM_IOJS_PREFIX}" | "${NVM_NODE_PREFIX}" | "system")
+ nvm_err "${1-} is a default (built-in) alias and cannot be deleted."
+ return 1
+ ;;
+ esac
+
[ ! -f "${NVM_ALIAS_DIR}/${1-}" ] && nvm_err "Alias ${1-} doesn't exist!" && return
local NVM_ALIAS_ORIGINAL
NVM_ALIAS_ORIGINAL="$(nvm_alias "${1}")"
diff --git "a/test/fast/Aliases/\"nvm unalias\" should not accept aliases with names equal to built-in alias" "b/test/fast/Aliases/\"nvm unalias\" should not accept aliases with names equal to built-in alias"
new file mode 100755
index 0000000..35bdc8f
--- /dev/null
+++ "b/test/fast/Aliases/\"nvm unalias\" should not accept aliases with names equal to built-in alias"
@@ -0,0 +1,25 @@
+#!/bin/sh
+
+\. ../../../nvm.sh
+
+die () { echo "$@" ; exit 1; }
+
+OUTPUT="$(nvm unalias node 2>&1)"
+EXPECTED_OUTPUT="node is a default (built-in) alias and cannot be deleted."
+[ "$OUTPUT" = "$EXPECTED_OUTPUT" ] || die "trying to remove a built-in alias should fail with '$EXPECTED_OUTPUT', got '$OUTPUT'"
+
+OUTPUT="$(nvm unalias stable 2>&1)"
+EXPECTED_OUTPUT="stable is a default (built-in) alias and cannot be deleted."
+[ "$OUTPUT" = "$EXPECTED_OUTPUT" ] || die "trying to remove a built-in alias should fail with '$EXPECTED_OUTPUT', got '$OUTPUT'"
+
+OUTPUT="$(nvm unalias unstable 2>&1)"
+EXPECTED_OUTPUT="unstable is a default (built-in) alias and cannot be deleted."
+[ "$OUTPUT" = "$EXPECTED_OUTPUT" ] || die "trying to remove a built-in alias should fail with '$EXPECTED_OUTPUT', got '$OUTPUT'"
+
+OUTPUT="$(nvm unalias iojs 2>&1)"
+EXPECTED_OUTPUT="iojs is a default (built-in) alias and cannot be deleted."
+[ "$OUTPUT" = "$EXPECTED_OUTPUT" ] || die "trying to remove a built-in alias should fail with '$EXPECTED_OUTPUT', got '$OUTPUT'"
+
+OUTPUT="$(nvm unalias system 2>&1)"
+EXPECTED_OUTPUT="system is a default (built-in) alias and cannot be deleted."
+[ "$OUTPUT" = "$EXPECTED_OUTPUT" ] || die "trying to remove a built-in alias should fail with '$EXPECTED_OUTPUT', got '$OUTPUT'"
