LOW risk. Read-only comparison.

diff

Q: What does diff do?

Compare files line by line and show differences. diff compares two files and outputs the differences in a format that can be applied as a patch. The -u flag produces unified diff format (the standard for patches and code review). Useful for config auditing, reviewing changes before applying, and generating patches.

Compare files line by line and show differences.

low risk

interactive breakdown — edit the command and press Explain

What it does

diff compares two files and outputs the differences in a format that can be applied as a patch. The -u flag produces unified diff format (the standard for patches and code review). Useful for config auditing, reviewing changes before applying, and generating patches.

Common flags

Flag	Meaning
`-u` `--unified`	Unified diff format (standard for patches)
`-r` `--recursive`	Compare directories recursively
`-i` `--ignore-case`	Ignore case differences
`-w` `--ignore-all-space`	Ignore all whitespace differences
`-q` `--brief`	Report only whether files differ

Examples

diff -u config.yaml.bak config.yamlShow changes since backup in patch format · explain & risk-check →

diff -r /etc/nginx.bak /etc/nginxCompare nginx config directories · explain & risk-check →

diff <(kubectl get cm myconfig -o yaml) config.yamlCompare live ConfigMap with local file · explain & risk-check →

diff -q dir1 dir2Quick check if directories differ · explain & risk-check →

Pro tip

Use `diff <(command1) <(command2)` with process substitution to compare command outputs without creating temp files — works for comparing live config with desired state.

git log patch sed

Open the full explainer →More in Text Processing

Reference text is hand-written and may be incomplete — check man diff for your version. Test destructive commands on a non-production system first.