bash
cat app.log | grep ERRORNotes
Use a pipeline to send command output into another command for filtering or transformation.
Linux Text Processing Cheat Sheet
Core Linux text processing commands and shell patterns for searching, filtering, editing, formatting, and analyzing text files and streams.
Export
Copy the compact sheet, download it, or print it.
Download
`D` dense toggle · `C` copy all
Overview and Core Patterns
Common text processing building blocks and pipeline patterns.
bash
grep ERROR app.logNotes
This is more efficient than using `cat file | grep ...` for most cases.
bash
journalctl -u nginx | awk '{print $1, $2, $3}'Notes
Most Linux text tools are designed for stream processing and work especially well in pipelines.
Save output and continue pipeline
Write output to a file while still passing it downstream.
bashANYteepipelinedebugging
bash
grep ERROR app.log | tee errors.txt | wc -lNotes
`tee` is useful when debugging pipelines or capturing intermediate results.
bash
ps aux
| grep python
| grep -v grep
| awk '{print $2, $11}'Notes
Long shell pipelines become much easier to read and maintain when formatted over multiple lines.
Line Selection and Context
Pick lines, ranges, and context quickly.
bash
head -n 20 server.logNotes
Useful for verifying file structure before applying heavier text processing.
bash
tail -n 50 server.logNotes
Often used with logs to inspect the most recent events.
bash
tail -f /var/log/nginx/access.logNotes
Use `-f` to stream appended data in real time.
bash
sed -n '100,120p' file.txtNotes
`sed -n` suppresses default output so only the requested range is printed.
bash
awk 'NR>=100 && NR<=120' file.txtNotes
Awk's `NR` variable tracks the current line number.
Formatting and Cleanup
Normalize spacing, wrap text, and clean lines.
bash
tr -s ' ' < input.txtNotes
Good for cleaning space-delimited text before further parsing.
Trim leading whitespace
Remove spaces and tabs from the start of each line.
bashANYsedtrimwhitespace
bash
sed 's/^[[:space:]]*//' file.txtNotes
Character classes make the expression portable across whitespace types.
bash
sed 's/[[:space:]]*$//' file.txtNotes
Useful before committing scripts, YAML, or source files.
bash
fmt -w 72 README.txtNotes
`fmt` is useful for quickly wrapping plain text to a target width.
bash
fold -w 80 long-lines.txtNotes
Unlike `fmt`, `fold` wraps mechanically rather than reflowing paragraphs.
More in Linux Text Processing
Linux Pipelines, xargs, split, diff, and Practical Recipes Cheat Sheet
Build practical shell pipelines, batch commands with xargs, compare files, and split or reshape data.
Linux cut, sort, uniq, tr, paste, join, and comm Cheat Sheet
Column extraction, sorting, deduplication, character translation, file combining, and list comparison.
Linux sed and awk Cheat Sheet
Edit text streams with sed and parse structured text with awk.
Linux grep and ripgrep Cheat Sheet
Search text with grep, egrep, fgrep, and ripgrep including regex, file globs, recursion, and context.