How to find PID's user name in linux

Can you help me to find the PID's user name, Some time my server got high load. When i top -c, I cannot even find the PID's user name who / which is causing load on the server.

I'm surprised nobody has put this up yet:

Try the -p option to the ps command.

For instance, if you have PID 1234, run:

ps -u -p 1234

(The -u was added to include the username in the output)

You can the use grep or awk, etc. to extract the info you want.

/proc/processID/status will have the information about user's ID which you can use to find the username.

This does the same:

uid=$(awk '/^Uid:/{print $2}' /proc/YOUR_PROCESS_ID/status)
getent passwd "$uid" | awk -F: '{print $1}'

Replace YOUR_PROCESS_ID with your process ID number.

Get only username from a PID:

PID=136323
USERNAME="$( ps -o uname= -p "${PID}" )"

You can also combine it with a pgrep. In this example we show all usernames executing some .php file:

pgrep -f '\.php' | xargs -r ps -o uname= -p | sort -u

Find only one username running a certain unique process:

USERNAME="$( pgrep -nf 'script\.php' | xargs -r ps -o uname= -p )