Heredocs, Herestrings & Process Substitution in Bash

From the Bash Scripting cheat sheet · Here-docs & Process Substitution · verified Jul 2026

Heredocs, Herestrings & Process Substitution

Feed blocks of text and command output.

bash

# Quick Reference
cat <<EOF
multi-line
text with $var expanded
EOF

grep foo <<< "$string"          # here-string
diff <(sort a) <(sort b)        # process substitution

💡 <<EOF expands $vars inside; <<'EOF' (quoted delimiter) keeps everything literal.

⚡ <<< "$str" (here-string) is a quick way to pipe one string into a command's stdin.

📌 <(cmd) turns command output into a temp file path - great for diff <(a) <(b).

🟢 <<-EOF strips leading tabs (only tabs, not spaces) so you can indent the block.

heredocprocess-substitution

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