与@netcoder讨论答案后，他使用了一个不错的技巧：D 使用fon ps总是可以使父项位于最前面。
这应该工作：
$ ps hf -opid -C <process> | awk '{ print $1; exit }'
我会去：
ps rf -opid,cmd -C <process-name> | awk '$2 !~ /^[|\\]/ { print $1 }'
那是：
然后
简单测试：
$ ps f -opid,cmd -Cchromium
PID CMD
2800 /usr/lib/chromium/chromium --type=zygote --enable-seccomp-sand@R_963_2419@
2803 \_ /usr/lib/chromium/chromium --type=zygote --enable-seccomp-sand@R_963_2419@
2899 \_ /usr/lib/chromium/chromium --type=renderer --enable-seccomp-sand@R_963_2419@ --lang=en-US --force-fieldtrials=ConnCountImpact/conn_count_6/ConnnectB
2906 | \_ /usr/lib/chromium/chromium --type=renderer --enable-seccomp-sand@R_963_2419@ --lang=en-US --force-fieldtrials=ConnCountImpact/conn_count_6/Connn
[ ... snip ... ]
2861 \_ /usr/lib/chromium/chromium --type=renderer --enable-seccomp-sand@R_963_2419@ --lang=en-US --force-fieldtrials=ConnCountImpact/conn_count_6/ConnnectB
2863 \_ /usr/lib/chromium/chromium --type=renderer --enable-seccomp-sand@R_963_2419@ --lang=en-US --force-fieldtrials=ConnCountImpact/conn_count_6/Connn
2794 /usr/lib/chromium/chromium --enable-seccomp-sand@R_963_2419@ --memory-model=low --purge-memory-button --disk-cache-dir=/tmp/chromium
2796 \_ /usr/lib/chromium/chromium --enable-seccomp-sand@R_963_2419@ --memory-model=low --purge-memory-button --disk-cache-dir=/tmp/chromium
3918 \_ /usr/lib/chromium/chromium --type=gpu-process --channel=2794.45.1891443837 --gpu-vendor-id=0x10de --gpu-device-id=0x0611 --gpu-driver-version -
25308 \_ [chromium] <defunct>
31932 \_ /usr/lib/chromium/chromium --type=plugin --plugin-path=/usr/lib/mozilla/plugins/libflashplayer.so --lang=en-US --channel=2794.1330.1990362572
$ ps f -opid,cmd -Cchromium | awk '$2 !~ /^[|\\]/ { print $1 }'
PID
2800
2794
$ # also supressing the header of ps (top line 'PID') -- add 'h' to ps
$ ps hf -opid,cmd -Cchromium | awk '$2 !~ /^[|\\]/ { print $1 }'
2800
2794
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