Format 'ps' command output without whitespace

Question

I have the following ps command to get particular properties of all the running processes along with some properties:

ps --no-headers -exo "uname,ppid,pid,etime,%cpu,%mem,args"

I wish to have it formatted in CSV so I can parse it. Note I have put the args at the end to make parsing easy; I don't think a , will exist in any of the other columns - please correct me if I am wrong.

How do I remove the whitespace?

Answer 1

From the man page:

-o format       user-defined format.
                format is a single argument in the form of a blank-separated or comma-separated list, which offers a
                way to specify individual output columns. The recognized keywords are described in the STANDARD FORMAT
                SPECIFIERS section below. Headers may be renamed (ps -o pid,ruser=RealUser -o comm=Command) as
                desired. If all column headers are empty (ps -o pid= -o comm=) then the header line will not be
                output. Column width will increase as needed for wide headers; this may be used to widen up columns
                such as WCHAN (ps -o pid,wchan=WIDE-WCHAN-COLUMN -o comm). Explicit width control
                (ps opid,wchan:42,cmd) is offered too. The behavior of ps -o pid=X,comm=Y varies with personality;
                output may be one column named "X,comm=Y" or two columns named "X" and "Y". Use multiple -o options
                when in doubt. Use the PS_FORMAT environment variable to specify a default as desired; DefSysV and
                DefBSD are macros that may be used to choose the default UNIX or BSD columns.

So try:

/bin/ps -o uname:1,ppid:1,pid:1

Answer 2

Since the first 6 fields should not contain blank characters (unless you allow them in user names), you can post-process the output:

ps --no-headers -exo "uname,ppid,pid,etime,%cpu,%mem,args" | sed '
  s/[\"]/\\&/g
  s/  */,/;s/  */,/;s/  */,/;s/  */,/;s/  */,/;s/  */,"/
  s/$/"/'

Here quoting the last field (args) after having escaped the "s and \s with \.

Produces an output like:

stephane,3641,3702,10-00:20:24,0.1,0.3,"some cmd,and,args... VAR=foo\"bar"

Answer 3

You can use sed with ps. So what you want is here:-

ps --no-headers -exo "uname,ppid,pid,etime,%cpu,%mem,args" | sed 's/\ /,/g'

But I wonder if it would be useful, as output of ps itself has got lots of ,.