Description

Launch apisix failed via systemctl start apisix, I got the logs like

May 03 15:00:00 lvs systemd[1]: Starting apisix...
May 03 15:00:00 lvs apisix[13574]: /usr/local/openresty/luajit/bin/luajit ./apisix/cli/apisix.lua start
May 03 15:00:01 lvs apisix[13574]: sh: lsof: command not found
May 03 15:00:01 lvs apisix[13574]: nginx.pid exists but there's no corresponding process with pid         3876        , the file will be overwritten
May 03 15:00:02 lvs systemd[1]: Started apisix.

1. lsof: command not found lsof tool not existed in minimal centos 7 environment. Better to check /proc/pid directory exist or not via lfs. attributes.

   apisix/rockspec/apisix-2.13.1-0.rockspec

   Line 51 in cc88a8d

   "luafilesystem = 1.7.0-2",

2. It should return while checking pid failed, log nginx.pid exists but there's no corresponding process with pid shouldn't output.
   

   apisix/apisix/cli/ops.lua

   Lines 723 to 738 in cc88a8d

   	if pid then
   	local lsof_cmd = "lsof -p " .. pid
   	local res, err = util.execute_cmd(lsof_cmd)
   	if not (res and res == "") then
   	if not res then
   	print(err)
   	else
   	print("APISIX is running...")
   	end
   	return
   	end
   	print("nginx.pid exists but there's no corresponding process with pid ", pid,
   	", the file will be overwritten")
   	end

Environment

• APISIX version (run apisix version): 2.13.1
• Operating system (run uname -a): Linux lvs 3.10.0-327.4.5.el7.x86_64
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):