Count the occurence of the lines.
Basically sortuniq is equivalent to sort | uniq and sortuniq -cn is equivalent to sort | uniq -c | sort -nr.
$ sortuniq -h
Usage:
sortuniq [OPTIONS]
Application Options:
-c, --count Prefix the number of occurrences
-n, --order Sort by the number of occurrences
-r, --reverse Reverse the order
Help Options:
-h, --help Show this help message
$ ps aux | awk '{print $1}' | sortuniq
USER
haccht
message+
root
syslog
systemd+
www-data
$ ps aux | awk '{print $1}' | sortuniq -cn
99 root
14 haccht
3 systemd+
2 www-data
1 syslog
1 message+
1 USER
Performance comparison:
$ time ( cat /dev/urandom | tr -dc '0-9' | fold -w 5 | head -n 10000000 | sortuniq -cn > /dev/null )
real 0m2.516s
user 0m1.891s
sys 0m0.594s
$ time ( cat /dev/urandom | tr -dc '0-9' | fold -w 5 | head -n 10000000 | sort | uniq -c | sort -nr > /dev/null )
real 0m20.529s
user 0m16.484s
sys 0m1.125s