cat /etc/passwd | grep root
cat /etc/passwd | grep ^root
cat /etc/passwd | grep -E "^(root|mysql)"
cat /etc/passwd | grep -E "^(root|mysql)>"
cat /etc/passwd | grep -n "^bin>"
cat /etc/passwd | grep -v "^root>"
cat /etc/passwd | grep -c "^root>"
cat /etc/passwd | grep -m 1 "^root>"
grep -r root /etc/
grep root /etc/libvirt/libvirtd.conf /etc/libvirt/libvirtd.conf /etc/libvirt/libvirt.conf
grep -l root /etc/libvirt/libvirtd.conf /etc/libvirt/libvirtd.conf /etc/libvirt/libvirt.conf
cat /etc/passwd | grep -v "/sbin/nologin$"
cat /etc/passwd | grep -E "[0-9]{2,3}"
cat /etc/passwd | grep -E "<[0-9]{2,3}>"
grep -r "^#[[:space:]].*" /etc
grep -Er "^[[:space:]]+[^[:space:]]" /etc/
cat /etc/ssh/sshd_config | grep -i s$
cat /etc/ssh/sshd_config | grep -E "(s|S)$"
cat /etc/ssh/sshd_config | grep "[sS]$"
cat /etc/passwd | grep -E "^(root|nobody|mysql)>"
cat /etc/init.d/functions | grep -E "^[a-zA-Z]+()"
cat /etc/passwd | grep -E "^([^:]+>).*1$"
