ps：process status
for pid in $(pgrep httpd); do echo -n "${pid} " ; ps -p ${pid} -o lstart | grep -v "START" ; done
ps -eo pid,lstart,etime,cmd | grep nginx
-e Display information about other users' processes, including those without controlling ter-
minals.
-o Display information associated with the space or comma separated list of keywords speci-
fied. Multiple keywords may also be given in the form of more than one -o option. Key-
words may be appended with an equals (`=') sign and a string. This causes the printed
header to use the specified string instead of the standard header. If all keywords have
empty header texts, no header line is written.
lstart STARTED time the command started. See also bsdstart, start, start_time, and stime.
etime ELAPSED elapsed time since the process was started, in the form [[DD-]hh:]mm:ss.
man -a ps查看ps的命令行手冊幫助信息