diff --git a/modules/igvf-chromap/run_chromap.py b/modules/igvf-chromap/run_chromap.py
index 6b4b4b7..5339b06 100644
--- a/modules/igvf-chromap/run_chromap.py
+++ b/modules/igvf-chromap/run_chromap.py
@@ -2,7 +2,9 @@
 import csv
 import gzip
 import logging
+import os
 import shutil
+import signal
 import sys
 import subprocess
 
@@ -10,6 +12,38 @@
 logging.basicConfig(stream=sys.stderr, level=logging.INFO)
 
 
+def run_shell_cmd(cmd):
+    p = subprocess.Popen(
+        ['/bin/bash', '-o', 'pipefail'],  # to catch error in pipe
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        universal_newlines=True,
+        preexec_fn=os.setsid)  # to make a new process with a new PGID
+    pid = p.pid
+    pgid = os.getpgid(pid)
+    logging.info('run_shell_cmd: PID={}, PGID={}, CMD={}'.format(pid, pgid, cmd))
+    stdout, stderr = p.communicate(cmd)
+    rc = p.returncode
+    err_str = (
+        'PID={pid}, PGID={pgid}, RC={rc}'
+        'STDERR={stde}\nSTDOUT={stdo}'
+    ).format(
+        pid=pid, pgid=pgid, rc=rc, stde=stderr.strip(), stdo=stdout.strip()
+    )
+    if rc:
+        # kill all child processes
+        try:
+            os.killpg(pgid, signal.SIGKILL)
+        except Exception:
+            pass
+        finally:
+            raise Exception(err_str)
+    else:
+        logging.info(err_str)
+    return stdout.strip('\n')
+
+
 def check_and_unzip(file_path):
     """
     Checks if a file is gzipped and unzips it if necessary.
@@ -148,11 +182,7 @@ def align(index_dir, read_format, reference_fasta, output_dir, subpool, threads,
 
     cmd = f"chromap -x {index_dir}/index --read_format {read_format} -r {reference_fasta} --remove-pcr-duplicates-at-cell-level --trim-adapters --low-mem --BED -l 2000 --bc-error-threshold 1 -t {threads} --bc-probability-threshold 0.90 -q 30 --barcode-whitelist {barcode_onlist} {barcode_translate_param} -o {output_dir}.fragments.tsv --summary {output_dir}.barcode.summary.csv -1 {read1} -2 {read2} -b {read_barcode} > {output_dir}.log.txt 2>&1"
     logging.info(f"Running command: {cmd}")
-    try:
-        result = subprocess.run(cmd, shell=True, capture_output=True, text=True, check=True)
-        logging.info(f"Command output: {result.stdout}")
-    except subprocess.CalledProcessError as e:
-        logging.error(f"Command failed with error: {e.stderr}")
+    run_shell_cmd(cmd)
 
     # Append the subpool to the barcodes in the fragment file.
     if subpool:
diff --git a/modules/igvf-kallisto-bustools/run_kallisto.py b/modules/igvf-kallisto-bustools/run_kallisto.py
index 0b79f0d..abaf747 100644
--- a/modules/igvf-kallisto-bustools/run_kallisto.py
+++ b/modules/igvf-kallisto-bustools/run_kallisto.py
@@ -3,7 +3,9 @@
 import h5py
 import logging
 import numpy as np
+import os
 import shutil
+import signal
 import sys
 import subprocess
 
@@ -11,6 +13,38 @@
 logging.basicConfig(stream=sys.stderr, level=logging.INFO)
 
 
+def run_shell_cmd(cmd):
+    p = subprocess.Popen(
+        ['/bin/bash', '-o', 'pipefail'],  # to catch error in pipe
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        universal_newlines=True,
+        preexec_fn=os.setsid)  # to make a new process with a new PGID
+    pid = p.pid
+    pgid = os.getpgid(pid)
+    logging.info('run_shell_cmd: PID={}, PGID={}, CMD={}'.format(pid, pgid, cmd))
+    stdout, stderr = p.communicate(cmd)
+    rc = p.returncode
+    err_str = (
+        'PID={pid}, PGID={pgid}, RC={rc}'
+        'STDERR={stde}\nSTDOUT={stdo}'
+    ).format(
+        pid=pid, pgid=pgid, rc=rc, stde=stderr.strip(), stdo=stdout.strip()
+    )
+    if rc:
+        # kill all child processes
+        try:
+            os.killpg(pgid, signal.SIGKILL)
+        except Exception:
+            pass
+        finally:
+            raise Exception(err_str)
+    else:
+        logging.info(err_str)
+    return stdout.strip('\n')
+
+
 def check_and_unzip(file_path):
     """
     Checks if a file is gzipped and unzips it if necessary.
@@ -100,6 +134,7 @@ def index_standard(output_dir, genome_fasta, gtf):
         logging.error(f"Archive command failed with error: {e.stderr}")
 
 
+
 @index.command("nac")
 @click.option('--output_dir', type=click.Path(exists=True), help='Path to the output directory.', required=True)
 @click.option('--genome_fasta', type=click.Path(exists=True), help='Path to the genome fasta file.', required=True)
@@ -127,6 +162,7 @@ def index_nac(output_dir, genome_fasta, gtf):
         logging.info(f"Command output: {result.stdout}")
     except subprocess.CalledProcessError as e:
         logging.error(f"Command failed with error: {e.stderr}")
+    
     # Archive the directory
     archive_cmd = f"tar -kzcvf {output_dir}.tar.gz {output_dir}"
     logging.info(f"Running archive command: {archive_cmd}")
@@ -177,11 +213,7 @@ def quantify_standard(index_dir, read_format, output_dir, strand, subpool, threa
     interleaved_fastqs_str = " ".join(interleaved_fastqs)
     cmd = f"kb count -i {index_dir}/index.idx -g {index_dir}/t2g.txt -x {read_format} -w {barcode_onlist} --strand {strand} {replacement_list_param} -o {output_dir} --h5ad -t {threads} {interleaved_fastqs_str}"
     logging.info(f"Running command: {cmd}")
-    try:
-        result = subprocess.run(cmd, shell=True, capture_output=True, text=True, check=True)
-        logging.info(f"Command output: {result.stdout}")
-    except subprocess.CalledProcessError as e:
-        logging.error(f"Command failed with error: {e.stderr}")
+    run_shell_cmd(cmd)
 
     # Append the subpool to the barcodes in the h5ad file
     if subpool:
@@ -245,13 +277,11 @@ def quantify_nac(index_dir, read_format, output_dir, strand, subpool, threads, b
     """
     logging.info("Running nac quantification pipeline.")
     # Create the command line string and run it using subprocess
-    cmd = f"kb count --workflow=nac -i {index_dir}/index.idx -g {index_dir}/t2g.txt -c1 {index_dir}/cdna.txt -c2 {index_dir}/nascent.txt --sum=total -x {read_format} -w {barcode_onlist} -r {replacement_list} --strand {strand} -o {output_dir} --h5ad -t {threads} {interleaved_fastqs}"
+    replacement_list_param = f"-r {replacement_list}" if replacement_list else ""
+    interleaved_fastqs_str = " ".join(interleaved_fastqs)
+    cmd = f"kb count --workflow=nac -i {index_dir}/index.idx -g {index_dir}/t2g.txt -c1 {index_dir}/cdna.txt -c2 {index_dir}/nascent.txt --sum=total -x {read_format} -w {barcode_onlist} {replacement_list_param} --strand {strand} -o {output_dir} --h5ad -t {threads} {interleaved_fastqs_str}"
     logging.info(f"Running command: {cmd}")
-    try:
-        result = subprocess.run(cmd, shell=True, capture_output=True, text=True, check=True)
-        logging.info(f"Command output: {result.stdout}")
-    except subprocess.CalledProcessError as e:
-        logging.error(f"Command failed with error: {e.stderr}")
+    run_shell_cmd(cmd)
 
     # Append the subpool to the barcodes in the h5ad file
     if subpool: