diff -uNr parallel-20180222/src/sem parallel-20180222.mod/src/sem
--- parallel-20180222/src/sem	2018-02-22 21:42:51.000000000 +0200
+++ parallel-20180222.mod/src/sem	2018-06-21 12:37:26.333395678 +0300
@@ -1137,7 +1137,7 @@
     if($opt::bug) { ::die_bug("test-bug"); }
     $Global::debug = $opt::D;
     $Global::shell = $ENV{'PARALLEL_SHELL'} || parent_shell($$)
-	|| $ENV{'SHELL'} || "/bin/sh";
+	|| $ENV{'SHELL'} || "@TERMUX_PREFIX@/bin/sh";
     if(not which($Global::shell)) {
 	::error("Shell '$Global::shell' not found.");
 	wait_and_exit(255);
@@ -1488,11 +1488,11 @@
     $Global::trim = 'n';
     $Global::max_jobs_running = 0;
     $Global::job_already_run = '';
-    $ENV{'TMPDIR'} ||= "/tmp";
+    $ENV{'TMPDIR'} ||= "@TERMUX_PREFIX@/tmp";
     if(not $ENV{HOME}) {
 	# $ENV{HOME} is sometimes not set if called from PHP
-	::warning("\$HOME not set. Using /tmp.");
-	$ENV{HOME} = "/tmp";
+	::warning("\$HOME not set. Using @TERMUX_HOME@.");
+	$ENV{HOME} = "@TERMUX_HOME@";
     }
     # no warnings to allow for undefined $XDG_*
     no warnings 'uninitialized';
@@ -3411,7 +3411,7 @@
     unlink $stderrname;
 
     my $pid = ::open3($stdin_fh,$stdout_fh,$stderr_fh,
-		      $0,qw(--plain --shell /bin/sh --will-cite), @args);
+		      $0,qw(--plain --shell @TERMUX_PREFIX@/bin/sh --will-cite), @args);
     if(my $writerpid = fork()) {
 	close $stdin_fh;
 	@stdout = <$stdout_fh>;