Unix tools do one job and read text from standard input, so they combine with |.
# the ten client IPs with most requests in an nginx access log
awk '{print $1}' /var/log/nginx/access.log | sort | uniq -c | sort -nr | head
grep -i "error" /var/log/syslog | tail -20 # case-insensitive match
grep -rn "listen 80" /etc/nginx/ # recursive, with line numbers
sed -i 's/PermitRootLogin yes/PermitRootLogin no/' /etc/ssh/sshd_config
cut -d: -f1,7 /etc/passwd # user and login shell| Tool | Best at |
|---|---|
grep |
Selecting lines |
sed |
Search and replace, line edits |
awk |
Working with columns |
sort, uniq |
Ordering and counting |
Test a sed -i edit without -i first, or use -i.bak to keep a backup copy of the file.