sponge — buffer stdin before writing: safe in-place pipeline transforms

linux-sponge.sh

# sponge — soak up all stdin, then write (from moreutils)
# sudo apt install moreutils

# THE PROBLEM: this destroys the file before sort reads it
sort file.txt > file.txt           # ⚠ race condition — file truncated on open

# THE FIX:
sort file.txt | sponge file.txt    # reads all input, then writes atomically

# In-place JSON formatting:
python3 -m json.tool config.json | sponge config.json

# In-place deduplication:
sort -u output.jsonl | sponge output.jsonl

# In-place cleanup:
grep -v 'DEBUG' app.log | sponge app.log

# Replaces the verbose temp-file pattern:
# cmd file > /tmp/out && mv /tmp/out file   →   cmd file | sponge file