grep — Pipelines

grep + xargs

grep + xargs — act on matched files

grep -rlP ':toc:' --include='*.adoc' docs/ | xargs -I{} sed -i '/:toc:/d' {}
# Find and remove :toc: from all files (STD-004 remediation)

Find and replace across files

grep -rl 'old_api' src/ | xargs sed -i 's/old_api/new_api/g'

grep + xargs — act on matched files with confirmation

grep -rlP 'hardcoded-ip' docs/ | xargs -p -I{} sed -i 's/10.50.1.50/{ise-primary-ip}/g' {}

grep + awk

grep + awk — extract and rank failed SSH login IPs

grep -P 'Failed password' /var/log/auth.log | awk '{print $11}' | sort | uniq -c | sort -rn | head

grep + awk — find files with >5 cross-references

grep -rcP --include='*.adoc' 'xref:' docs/modules/ROOT/pages/ | awk -F: '$2 > 5'

find + grep

find + grep — search with filesystem predicates

find docs/ -name '*.adoc' -mtime -7 -exec grep -lP 'TODO' {} +
# Recently modified files with TODOs

grep + process substitution — diff two searches

diff <(grep -rlP 'include::partial\$' docs/modules/ROOT/pages/) \
     <(grep -rlP 'include::example\$' docs/modules/ROOT/pages/)
# Pages that use partials vs examples

Conditional Scripting

Quiet test in conditionals

grep -qP 'PermitRootLogin\s+no' /etc/ssh/sshd_config && echo "secure" || echo "FIX THIS"

Guard for idempotent operations

grep -qF '10.50.1.91 mail-01' /etc/hosts || echo '10.50.1.91 mail-01.inside.domusdigitalis.dev mail-01' | sudo tee -a /etc/hosts

Process matching files in a loop

grep -rlP --include='*.adoc' '^\|.*`[^`]*(?<!\\)\|[^`]*`' docs/ | while read -r f; do
    echo "=== Unescaped pipes in: $f ==="
    grep -nP '^\|.*`[^`]*(?<!\\)\|[^`]*`' "$f"
done

Exit code in pipelines — grep returns 0 (found), 1 (not found), 2 (error)

if grep -qP 'ERROR|FATAL' /var/log/app.log; then
    systemctl restart app
fi

Runbook Navigation

Find all phases

grep -n '^=== Phase' runbook.adoc

Find phase with 30 lines of context

grep -n -A30 '^=== Phase 3:' runbook.adoc

List phase titles only

grep -oE '^=== Phase [0-9]+:.*' runbook.adoc

Count phases

grep -c '^=== Phase' runbook.adoc

Show all section headers (document outline)

grep -nE '^={2,4} ' runbook.adoc

Find pre/post validation sections

grep -n -A10 'Pre-Validation' runbook.adoc
grep -n -A10 'Post-Validation' runbook.adoc