Open navigation menu

Process Substitution for Pipelines

Uses process substitution to feed command output as files to commands expecting file arguments, enabling complex data comparison and merging operations.

BashCli Tooling

Code

snippet
#!/usr/bin/env bash
set -euo pipefail

# Compare command outputs without temp files
diff <(ls /etc/*.conf 2>/dev/null | sort) <(ls /etc/*.cfg 2>/dev/null | sort) || true

# Feed generated data to commands expecting files
sort <(echo -e "cherry\napple\nbanana")

# Merge sorted streams
sort -m <(echo -e "1\n3\n5") <(echo -e "2\n4\n6")

# Process substitution with while loop
while read -r line; do
    echo "Processing: $line"
done < <(seq 1 5)

# Use with paste to combine columns
paste <(seq 1 5) <(seq 6 10) | while read -r a b; do
    echo "$a + $b = $((a + b))"
done

# Tee with process substitution for logging
echo "Important data" | tee >(gzip > /tmp/output.gz) > /tmp/output.txt

echo "Process substitution complete"

Related Examples