After installing mysql in source code, problems may occur during startup.

After mysql is installed in the source code, a problem occurs during startup-general Linux technology-Linux technology and application information. For more information, see the following. For example, if the source code on RHEL is used to install mysql and set it as a system service (the original mysql was deleted by rpm-e), the following error is reported during startup:
[Root @ localhost log] # service mysqld start
Starting MySQL/etc/init. d/mysqld: line 161: kill: (1639)-No such process
[Failed]
The following is the content of mysqld's 161 rows and its proximity:
154 wait_for_pid (){
155 I = 0
156 while test $ I-ne $ service_startup_timeout; do
157 sleep 1
158 case "$1" in
159 'created ')
160 test-s $ pid_file & I = ''& break
161 kill-0 $2 | break # if the program goes away, stop waiting
162 ;;
163 'removed ')
164 test! -S $ pid_file & I = ''& break
165 ;;
166 *)
167 echo "wait_for_pid () usage: wait_for_pid created | removed"
168 exit 1
169 ;;
The following is the startup process using mysqld_safe.
[Root @ localhost bin] # mysqld_safe-u root &
[1] 1718
[Root @ localhost bin] # Starting mysqld daemon with databases from/usr/local/mysql/var
And then it stops here.
What is the reason?