pwd: support the env variable 'POSIXLY_CORRECT'

Should fix tests/misc/pwd-option.sh

src/uu/pwd/src/pwd.rs

@@ -126,7 +126,10 @@ fn logical_path() -> io::Result<PathBuf> {
 #[uucore::main]
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     let matches = uu_app().try_get_matches_from(args)?;
-    let cwd = if matches.get_flag(OPT_LOGICAL) {
+    // if POSIXLY_CORRECT is set, we want to a logical resolution.
+    // This produces a different output when doing mkdir -p a/b && ln -s a/b c && cd c && pwd
+    // We should get c in this case instead of a/b at the end of the path
+    let cwd = if matches.get_flag(OPT_LOGICAL) || env::var("POSIXLY_CORRECT").is_ok() {
         logical_path()
     } else {
         physical_path()

tests/by-util/test_pwd.rs

@@ -90,6 +90,35 @@ fn test_symlinked_default() {
     env.ucmd.succeeds().stdout_is(env.subdir + "\n");
 }
 
+#[test]
+fn test_symlinked_default_posix() {
+    let mut env = symlinked_env();
+    env.ucmd
+        .env("POSIXLY_CORRECT", "1")
+        .succeeds()
+        .stdout_is(env.symdir.clone() + "\n");
+}
+
+#[test]
+fn test_symlinked_default_posix_l() {
+    let mut env = symlinked_env();
+    env.ucmd
+        .env("POSIXLY_CORRECT", "1")
+        .arg("-L")
+        .succeeds()
+        .stdout_is(env.symdir + "\n");
+}
+
+#[test]
+fn test_symlinked_default_posix_p() {
+    let mut env = symlinked_env();
+    env.ucmd
+        .env("POSIXLY_CORRECT", "1")
+        .arg("-P")
+        .succeeds()
+        .stdout_is(env.symdir + "\n");
+}
+
 #[cfg(not(windows))]
 pub mod untrustworthy_pwd_var {
     use std::path::Path;