Backport 2.1: Use "#!/usr/bin/env perl" as shebang line.
diff --git a/ChangeLog b/ChangeLog
index 0c247f9..704ecc9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -51,6 +51,8 @@
    * Improve robustness of mbedtls_ssl_derive_keys against the use of
      HMAC functions with non-HMAC ciphersuites. Independently contributed
      by Jiayuan Chen in #1377. Fixes #1437.
+   * Change the shebang line in Perl scripts to look up perl in the PATH.
+     Contributed by fbrosson in #1533.
 
 = mbed TLS 2.1.11 branch released 2018-03-16
 
diff --git a/scripts/config.pl b/scripts/config.pl
index dcf0281..d9da997 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # This file is part of mbed TLS (https://tls.mbed.org)
 #
diff --git a/scripts/generate_errors.pl b/scripts/generate_errors.pl
index cc9527e..3687bd4 100755
--- a/scripts/generate_errors.pl
+++ b/scripts/generate_errors.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Generate error.c
 #
diff --git a/scripts/generate_features.pl b/scripts/generate_features.pl
index 2aa695c..1bd82ca 100755
--- a/scripts/generate_features.pl
+++ b/scripts/generate_features.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 
 use strict;
diff --git a/scripts/generate_visualc_files.pl b/scripts/generate_visualc_files.pl
index 8d36653..5e3b9b5 100755
--- a/scripts/generate_visualc_files.pl
+++ b/scripts/generate_visualc_files.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Generate files for MS Visual Studio:
 # - for VS6: main project (library) file, individual app files, workspace
diff --git a/scripts/massif_max.pl b/scripts/massif_max.pl
index d1ce4ca..4e3342a 100755
--- a/scripts/massif_max.pl
+++ b/scripts/massif_max.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Parse a massif.out.xxx file and output peak total memory usage
 
diff --git a/scripts/rename.pl b/scripts/rename.pl
index c169078..22a86cc 100755
--- a/scripts/rename.pl
+++ b/scripts/rename.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # rename identifiers (functions, types, enum constant, etc)
 # on upgrades of major version according to a list
diff --git a/tests/scripts/check-doxy-blocks.pl b/tests/scripts/check-doxy-blocks.pl
index b0fd696..4967699 100755
--- a/tests/scripts/check-doxy-blocks.pl
+++ b/tests/scripts/check-doxy-blocks.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Detect comment blocks that are likely meant to be doxygen blocks but aren't.
 #
diff --git a/tests/scripts/curves.pl b/tests/scripts/curves.pl
index c9554e0..f2008dc 100755
--- a/tests/scripts/curves.pl
+++ b/tests/scripts/curves.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # curves.pl
 #
diff --git a/tests/scripts/depends-hashes.pl b/tests/scripts/depends-hashes.pl
index 29dcfb0..f57e7ed 100755
--- a/tests/scripts/depends-hashes.pl
+++ b/tests/scripts/depends-hashes.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # depends-hashes.pl
 #
diff --git a/tests/scripts/depends-pkalgs.pl b/tests/scripts/depends-pkalgs.pl
index 14c92b2..97a43e8 100755
--- a/tests/scripts/depends-pkalgs.pl
+++ b/tests/scripts/depends-pkalgs.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # depends-pkalgs.pl
 #
diff --git a/tests/scripts/gen_ctr_drbg.pl b/tests/scripts/gen_ctr_drbg.pl
index 66d9b3a..08ca5df 100755
--- a/tests/scripts/gen_ctr_drbg.pl
+++ b/tests/scripts/gen_ctr_drbg.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Based on NIST CTR_DRBG.rsp validation file
 # Only uses AES-256-CTR cases that use a Derivation function
diff --git a/tests/scripts/gen_gcm_decrypt.pl b/tests/scripts/gen_gcm_decrypt.pl
index 6decac2..03809cb 100755
--- a/tests/scripts/gen_gcm_decrypt.pl
+++ b/tests/scripts/gen_gcm_decrypt.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Based on NIST gcmDecryptxxx.rsp validation files
 # Only first 3 of every set used for compile time saving
diff --git a/tests/scripts/gen_gcm_encrypt.pl b/tests/scripts/gen_gcm_encrypt.pl
index 8adbbce..29ec677 100755
--- a/tests/scripts/gen_gcm_encrypt.pl
+++ b/tests/scripts/gen_gcm_encrypt.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 # Based on NIST gcmEncryptIntIVxxx.rsp validation files
 # Only first 3 of every set used for compile time saving
diff --git a/tests/scripts/gen_pkcs1_v21_sign_verify.pl b/tests/scripts/gen_pkcs1_v21_sign_verify.pl
index 0d7fc7d..95c5235 100755
--- a/tests/scripts/gen_pkcs1_v21_sign_verify.pl
+++ b/tests/scripts/gen_pkcs1_v21_sign_verify.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 #
 
 use strict;
diff --git a/tests/scripts/key-exchanges.pl b/tests/scripts/key-exchanges.pl
index d167c67..3bf7ae3 100755
--- a/tests/scripts/key-exchanges.pl
+++ b/tests/scripts/key-exchanges.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # key-exchanges.pl
 #
diff --git a/tests/scripts/list-enum-consts.pl b/tests/scripts/list-enum-consts.pl
index 633e3fd..21c25b3 100755
--- a/tests/scripts/list-enum-consts.pl
+++ b/tests/scripts/list-enum-consts.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use warnings;
 use strict;
diff --git a/tests/scripts/recursion.pl b/tests/scripts/recursion.pl
index 3ad42b1..431e592 100755
--- a/tests/scripts/recursion.pl
+++ b/tests/scripts/recursion.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # Find functions making recursive calls to themselves.
 # (Multiple recursion where a() calls b() which calls a() not covered.)
diff --git a/tests/scripts/run-test-suites.pl b/tests/scripts/run-test-suites.pl
index 5b55fac..d53bedc 100644
--- a/tests/scripts/run-test-suites.pl
+++ b/tests/scripts/run-test-suites.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 use warnings;
 use strict;
diff --git a/tests/scripts/test-ref-configs.pl b/tests/scripts/test-ref-configs.pl
index 5b35a60..7d6eb66 100755
--- a/tests/scripts/test-ref-configs.pl
+++ b/tests/scripts/test-ref-configs.pl
@@ -1,4 +1,4 @@
-#!/usr/bin/perl
+#!/usr/bin/env perl
 
 # test standard configurations:
 # - build