diff --git a/src/parallel b/src/parallel
index 34700c7b..7f9375ea 100755
--- a/src/parallel
+++ b/src/parallel
@@ -2212,6 +2212,12 @@ sub init_globals() {
 	 '{choose_k}' => 'for $t (2..$#arg){ if($arg[$t-1] ge $arg[$t]) { skip() } }',
 	 # {##} = number of jobs
 	 '{##}' => '$_=total_jobs()',
+	 # {0%} = 0-padded jobslot
+	 '{0%}' => '$f=1+int((log($Global::max_jobs_running||1)/log(10))); $_=sprintf("%0${f}d",slot())',
+	 # {0%} = 0-padded seq
+	 '{0#}' => '$f=1+int((log(total_jobs())/log(10))); $_=sprintf("%0${f}d",seq())',
+
+	 ## Bash inspired replacement strings
 	 # Bash ${a:-myval}
 	 '{:-([^}]+?)}' => '$_ ||= $$1',
 	 # Bash ${a:2}
@@ -6301,6 +6307,7 @@ sub set_max_jobs_running($$) {
         $Global::max_jobs_running -= $self->{'max_jobs_running'};
     }
     $self->{'max_jobs_running'} = shift;
+
     if(defined $self->{'max_jobs_running'}) {
         # max_jobs_running could be resat if -j is a changed file
         $Global::max_jobs_running += $self->{'max_jobs_running'};
@@ -10811,12 +10818,13 @@ sub new($) {
 
 sub flush_cache() {
     my $self = shift;
-    for my $arglist (@{$self->{'arglist'}}) {
+    for my $arglist (@{$self->{'arg_list'}}) {
 	for my $arg (@$arglist) {
 	    $arg->flush_cache();
 	}
     }
     $self->{'arg_queue'}->flush_cache();
+    $self->{'replaced'} = undef;
 }
 
 sub seq($) {
@@ -13657,6 +13665,7 @@ sub main() {
     # Compute $Global::max_jobs_running
     # Must be done after ungetting any --pipepart jobs.
     max_jobs_running();
+
     init_run_jobs();
     my $sem;
     if($Global::semaphore) {
diff --git a/src/parallel.pod b/src/parallel.pod
index df65ade5..fc8ea174 100644
--- a/src/parallel.pod
+++ b/src/parallel.pod
@@ -299,14 +299,20 @@ directory (if any) and extension removed.
 To understand positional replacement strings see B<{>I<n>B<}>.
 
 
-=item B<{=>I<perl expression>B<=}>
+=item B<{=>I<perl expression>B<=}> (alpha testing)
 
 Replace with calculated I<perl expression>. B<$_> will contain the
 same as B<{}>. After evaluating I<perl expression> B<$_> will be used
 as the value. It is recommended to only change $_ but you have full
 access to all of GNU B<parallel>'s internal functions and data
-structures. A few convenience functions and data structures have been
-made:
+structures.
+
+The expression must give the same result if evaluated twice -
+otherwise the behaviour is undefined. E.g. this will not work as expected:
+
+    parallel echo '{= $_= ++$wrong_counter =}' ::: a b c
+
+A few convenience functions and data structures have been made:
 
 =over 15
 
@@ -870,7 +876,7 @@ replacement strings and Perl code. Example:
 
    parallel --filter '{1} < {2}+1' echo ::: {1..3} ::: {1..3}
 
-Runs: 1,1 1,2 1,3 2,2 2,3 3,3
+Outputs: 1,1 1,2 1,3 2,2 2,3 3,3
 
 
 =item B<--filter-hosts>
@@ -1625,11 +1631,9 @@ Activate additional replacement strings: {+/} {+.} {+..} {+...} {..}
 B<{##}> is the total number of jobs to be run. It is incompatible with
 B<-X>/B<-m>/B<--xargs>.
 
-B<{0%}>, B<{00%}>, B<{000%}>, ... B<{0..0%}> prefix jobslot with
-zeros. (alpha testing)
+B<{0%}> zero-padded jobslot. (alpha testing)
 
-B<{0#}>, B<{00#}>, B<{000#}>, ... B<{0..0#}> prefix sequence numbers
-with zeros. (alpha testing)
+B<{0#}> zero-padded sequence number. (alpha testing)
 
 B<{choose_k}> is inspired by n choose k: Given a list of n elements,
 choose k. k is the number of input sources and n is the number of
@@ -2640,6 +2644,23 @@ will be replaced.
 
 With B<--cleanup> the new file will be removed when the job is done.
 
+If I<my.tmpl> contains this:
+
+  Xval: {x}
+  Yval: {y}
+  FixedValue: 9
+  # x with 2 decimals
+  DecimalX: {=x $_=sprintf("%.2f",$_) =}
+  TenX: {=x $_=$_*10 =}
+  RandomVal: {=1 $_=rand() =}
+
+it can be used like this:
+
+  myprog() { echo Using "$@"; cat "$@"; }
+  export -f myprog
+  parallel --cleanup --header : --tmpl my.tmpl={#}.t myprog {#}.t \
+    ::: x 1.234 2.345 3.45678 ::: y 1 2 3
+
 
 =item B<--tty>
 
diff --git a/src/parallel_alternatives.pod b/src/parallel_alternatives.pod
index 6e03ad12..6132376f 100644
--- a/src/parallel_alternatives.pod
+++ b/src/parallel_alternatives.pod
@@ -2862,10 +2862,8 @@ Distributed Resource Management Application API to make jobs run with
 different cluster software.
 
 
-=head3 Future support in GNU Parallel
-
-B<Future> versions of GNU B<parallel> may support templates
-with replacement strings. Such as:
+GNU B<parallel> B<--tmpl> supports templates with replacement
+strings. Such as:
 
   Xval: {x}
   Yval: {y}
@@ -2873,21 +2871,17 @@ with replacement strings. Such as:
   # x with 2 decimals
   DecimalX: {=x $_=sprintf("%.2f",$_) =}
   TenX: {=x $_=$_*10 =}
-  RandomVal: {= $_=rand() =}
+  RandomVal: {=1 $_=rand() =}
 
 that can be used like:
 
   parallel --header : --tmpl my.tmpl={#}.t myprog {#}.t \
     ::: x 1 2 3 ::: y 1 2 3
 
-Filtering may also be supported as:
+Filtering is supported as:
 
   parallel --filter '{1} > {2}' echo ::: 1 2 3 ::: 1 2 3
 
-which will basically do:
-
-  parallel echo '{= $arg[1] > $arg[2] and skip() =}' ::: 1 2 3 ::: 1 2 3
-
 https://github.com/eviatarbach/parasweep (Last checked: 2021-01)
 
 
@@ -2936,6 +2930,28 @@ https://reposhub.com/python/command-line-tools/Akianonymus-parallel-bash.html
 (Last checked: 2021-02)
 
 
+=head2 DIFFERENCES BETWEEN bash-concurrent AND GNU Parallel
+
+B<bash-concurrent> is more an alternative to B<make> than to GNU
+B<parallel>. Its input is very similar to a Makefile, where jobs
+depend on other jobs.
+
+It has a nice progress indicator where you can see which jobs
+completed successfully, which jobs are currently running, which jobs
+failed, and which jobs were skipped due to a depending job failed.
+The indicator does not deal well with resizing the window.
+
+Output is cached in tempfiles on disk, but is only shown if there is
+an error, so it is not meant to be part of a UNIX pipeline. If
+B<bash-concurrent> crashes these tempfiles are not removed.
+
+It uses an O(n*n) algorithm, so if you have 1000 independent jobs it
+takes 22 seconds to start it.
+
+https://github.com/themattrix/bash-concurrent
+(Last checked: 2021-02)
+
+
 =head2 Todo
 
 https://github.com/Nukesor/pueue
diff --git a/testsuite/tests-to-run/parallel-local-0.3s.sh b/testsuite/tests-to-run/parallel-local-0.3s.sh
index bc39e6f1..36eb75fb 100644
--- a/testsuite/tests-to-run/parallel-local-0.3s.sh
+++ b/testsuite/tests-to-run/parallel-local-0.3s.sh
@@ -69,12 +69,12 @@ EOF
     cat <<'EOF' > "$tmp2"
     2: Job:{#} Slot:{%} All:{} Arg[1]:{1} Arg[-1]:{-1} Perl({}+4):{=$_+=4=}
 EOF
-    parallel -j2 --cleanup --tmpl $tmp1=t1.{#} --tmpl $tmp2=t2.{%} \
-	     'cat t1.{#} t2.{%}' ::: 1 2 ::: a b
+    parallel --colsep , -j2 --cleanup --tmpl $tmp1=t1.{#} --tmpl $tmp2=t2.{%} \
+	     'sleep 0.{#}; cat t1.{#} t2.{%}' ::: 1,a 1,b 2,a 2,b
     echo should give no files
     ls t[12].*
-    parallel --cleanup --colsep , -j2 --tmpl $tmp1=t1.{#} --tmpl $tmp2=t2.{%} \
-	     'cat t1.{#} t2.{%}' ::: 1,a 1,b 2,a 2,b
+    parallel            -j2 --cleanup --tmpl $tmp1=t1.{#} --tmpl $tmp2=t2.{%} \
+	     'sleep 0.{#}; cat t1.{#} t2.{%}' ::: 1 2 ::: a b
     echo should give no files
     ls t[12].*
 }
diff --git a/testsuite/wanted-results/parallel-local-1s b/testsuite/wanted-results/parallel-local-1s
index 9187ae5f..1e74499c 100644
--- a/testsuite/wanted-results/parallel-local-1s
+++ b/testsuite/wanted-results/parallel-local-1s
@@ -282,6 +282,10 @@ par_open_files_blocks	9 of 21
 par_open_files_blocks	10 of 21
 par_open_files_blocks	11 of 21
 par_open_files_blocks	12 of 21
+par_open_files_blocks	parallel: Warning: Try running 'parallel -j0 -N 100 --pipe parallel -j0'
+par_open_files_blocks	parallel: Warning: or increasing 'ulimit -n' (try: ulimit -n `ulimit -Hn`)
+par_open_files_blocks	parallel: Warning: or increasing 'nofile' in /etc/security/limits.conf
+par_open_files_blocks	parallel: Warning: or increasing /proc/sys/fs/file-max
 par_open_files_blocks	13 of 21
 par_open_files_blocks	14 of 21
 par_open_files_blocks	15 of 21
@@ -479,21 +483,21 @@ par_plus_slot_replacement	Seq: 097 97
 par_plus_slot_replacement	Seq: 098 98
 par_plus_slot_replacement	Seq: 099 99
 par_plus_slot_replacement	Seq: 100 100
-par_plus_slot_replacement	Slot: 1 1
+par_plus_slot_replacement	Slot: 01 1
+par_plus_slot_replacement	Slot: 02 2
+par_plus_slot_replacement	Slot: 03 3
+par_plus_slot_replacement	Slot: 04 4
+par_plus_slot_replacement	Slot: 05 5
+par_plus_slot_replacement	Slot: 06 6
+par_plus_slot_replacement	Slot: 07 7
+par_plus_slot_replacement	Slot: 08 8
+par_plus_slot_replacement	Slot: 09 9
 par_plus_slot_replacement	Slot: 10 10
 par_plus_slot_replacement	Slot: 11 11
 par_plus_slot_replacement	Slot: 12 12
 par_plus_slot_replacement	Slot: 13 13
 par_plus_slot_replacement	Slot: 14 14
 par_plus_slot_replacement	Slot: 15 15
-par_plus_slot_replacement	Slot: 2 2
-par_plus_slot_replacement	Slot: 3 3
-par_plus_slot_replacement	Slot: 4 4
-par_plus_slot_replacement	Slot: 5 5
-par_plus_slot_replacement	Slot: 6 6
-par_plus_slot_replacement	Slot: 7 7
-par_plus_slot_replacement	Slot: 8 8
-par_plus_slot_replacement	Slot: 9 9
 par_profiles_with_space	### bug #42902: profiles containing arguments with space
 par_profiles_with_space	/bin/bash=/bin/bash
 par_profiles_with_space	echo '/bin/bash=/bin/bash'