README updated for pgrep user support

closes influxdata#724

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 - [#727](https://github.com/influxdata/telegraf/pull/727): riak input, thanks @jcoene!
 - [#694](https://github.com/influxdata/telegraf/pull/694): DNS Query input, thanks @mjasion!
+- [#724](https://github.com/influxdata/telegraf/pull/724): username matching for procstat input, thanks @zorel!
 
 ### Bugfixes
 - [#701](https://github.com/influxdata/telegraf/pull/701): output write count shouldnt print in quiet mode.

plugins/inputs/procstat/README.md

@@ -7,7 +7,8 @@ individual process using their /proc data.
 
 The plugin will tag processes by their PID and their process name.
 
-Processes can be specified either by pid file or by executable name. Procstat
+Processes can be specified either by pid file, by executable name, by command
+line pattern matching, or by username (in this order or priority. Procstat
 plugin will use `pgrep` when executable name is provided to obtain the pid.
 Proctstas plugin will transmit IO, memory, cpu, file descriptor related
 measurements for every process specified. A prefix can be set to isolate

plugins/inputs/procstat/procstat.go

@@ -56,7 +56,7 @@ func (_ *Procstat) Description() string {
 func (p *Procstat) Gather(acc telegraf.Accumulator) error {
 	err := p.createProcesses()
 	if err != nil {
-	log.Printf("Error: procstat getting process, exe: [%s]	pidfile: [%s] pattern: [%s] user: [%s] %s",
+		log.Printf("Error: procstat getting process, exe: [%s]	pidfile: [%s] pattern: [%s] user: [%s] %s",
 			p.Exe, p.PidFile, p.Pattern, p.User, err.Error())
 	} else {
 		for _, proc := range p.pidmap {