Greg Wooledge <g...@wooledge.org> writes: > On Sun, Feb 19, 2023 at 12:04:22PM -0600, David Wright wrote: >> But even that's not enough >> because the field width is somewhat variable: try ps -eo '%c | %z | %a' >> (We can still use | to make the problem somewhat more obvious.) > > Oh wow. Yeah, OK, that's not really solvable. > > For those who don't want to try to reverse engineer David's conclusion, > or who don't just happen to stumble upon it with their current process > list, here's what I'm seeing: > > COMMAND | VSZ | COMMAND > systemd | 164140 | /sbin/init > kthreadd | 0 | [kthreadd] > rcu_gp | 0 | [rcu_gp] > rcu_par_gp | 0 | [rcu_par_gp] > [...] > steamwebhelper | 4631064 | /home/greg/.steam/debian-installation/[...] > [...] > chrome_crashpad | 33567792 | > /opt/google/chrome/chrome_crashpad_handler[...] > [...] > kworker/3:0-eve | 0 | [kworker/3:0-events] > > ps appears to guess an initial maximum width for the VSZ field, but > when a value comes along that exceeds the guessed maximum, it simply > shoves the field barrier over. It doesn't even become the new maximum, > with all of the fields aligning after that. It's just a one-time shove, > breaking the current line only. > > Therefore, parsing the header line cannot give us enough information to > insert field separators correctly in body lines after the fact.
Dear all, Thanks for chiming in. The example was indeed simplified and I am using %a which can contain internal whitespace. This is the command I was using previously: ps -eo '%p|%c|%C' -o "%mem" -o '|%a' --sort=-%cpu I now replaced it with ps -eo '%p %c %C' -o "%mem" -o ' %a' --sort=-%cpu | sed -E 's/([0-9]+) (.+) ([0-9]+.?[0-9]?) ([0-9]+.?[0-9]?) (.+)/\1|\2|\3|\4|\5/' This works, but is of course cumbersome to maintain. Again, thanks for all the comments! Best, Andreas
