Distributed by Chr (sh)

How is the SAMtools dependency provided?

The SAMtools dependency is resolved by declaring an Apt-Get package in the dxapp.json file’s runSpec.execDepends.
"runSpec": {
"execDepends": [
{"name": "samtools"}
For additional information, see execDepends

Entry Points

Distributed bash-interpreter apps use bash functions to declare entry points. This app has the following entry points specified as bash functions:
  • main
  • count_func
  • sum_reads
Entry points are executed on a new worker with its own system requirements. The instance type can be set in the dxapp.json file’s runSpec.systemRequirements:
"runSpec": {
"systemRequirements": {
"main": {
"instanceType": "mem1_ssd1_x4"
"count_func": {
"instanceType": "mem1_ssd1_x2"
"sum_reads": {
"instanceType": "mem1_ssd1_x4"


The main function slices the initial *.bam file and generates an index *.bai if needed. The input *.bam is the sliced into smaller *.bam files containing only reads from canonical chromosomes. First, the main function downloads the BAM file and gets the headers.
dx download "${mappings_sorted_bam}"
chromosomes=$(samtools view -H "${mappings_sorted_bam_name}" | grep "\@SQ" | awk -F '\t' '{print $2}' | awk -F ':' '{if ($2 ~ /^chr[0-9XYM]+$|^[0-9XYM]/) {print $2}}')
Sliced *.bam files are uploaded and their file IDs are passed to the count_func entry point using the dx-jobutil-new-job command.
if [ -z "${mappings_sorted_bai}" ]; then
samtools index "${mappings_sorted_bam_name}"
dx download "${mappings_sorted_bai}" -o "${mappings_sorted_bam_name}".bai
for chr in $chromosomes; do
samtools view -b "${mappings_sorted_bam_name}" "${chr}" > "${seg_name}"
bam_seg_file=$(dx upload "${seg_name}" --brief)
count_jobs+=($(dx-jobutil-new-job -isegmentedbam_file="${bam_seg_file}" -ichr="${chr}" count_func))
Outputs from the count_func entry points are referenced as Job Based Object References (JBOR) and used as inputs for the sum_reads entry point.
for job in "${count_jobs[@]}"; do
sum_reads_job=$(dx-jobutil-new-job "${readfiles[@]}" -ifilename="${mappings_sorted_bam_prefix}" sum_reads)
The output of the sum_reads entry point is used as the output of the main entry point via JBOR reference using the command dx-jobutil-add-output.


This entry point downloads and runs the command samtools view -c on the sliced *.bam. The generated counts_txt output file is uploaded as the entry point’s job output via the command dx-jobutil-add-output.
count_func ()
echo "Value of segmentedbam_file: '${segmentedbam_file}'";
echo "Chromosome being counted '${chr}'";
dx download "${segmentedbam_file}";
readcount=$(samtools view -c "${segmentedbam_file_name}");
printf "${chr}:\t%s\n" "${readcount}" > "${segmentedbam_file_prefix}.txt";
readcount_file=$(dx upload "${segmentedbam_file_prefix}".txt --brief);
dx-jobutil-add-output counts_txt "${readcount_file}" --class=file


The main entry point triggers this sub job, providing the output of count_func as an input. This entry point gathers all the files generated by the count_func jobs and sums them.
This function returns read_sum_file as the entry point output.
sum_reads ()
set -e -x -o pipefail;
printf "Value of read file array %s" "${readfiles[@]}";
echo "Filename: ${filename}";
echo "Summing values in files and creating output read file";
for read_f in "${readfiles[@]}";
echo "${read_f}";
dx download "${read_f}" -o - >> chromosome_result.txt;
total=$(awk '{s+=$2} END {print s}' chromosome_result.txt);
echo "Total reads: ${total}" >> "${count_file}";
readfile_name=$(dx upload "${count_file}" --brief);
dx-jobutil-add-output read_sum_file "${readfile_name}" --class=file