ps does not show name of the shell script only -bash or bash - Linux

Recently, on a CentOS box I've noticed that when I run ps -ef or ps axuw some of my scripts don't show up. I also checked this on Ubuntu 19.04 with similar results.

TLDR: add #!/bin/bash as the first line of your Bash script.

I ran a little experiment.

Created a script called hello.sh with the following content:

examples/shell/hello.sh

echo $$
sleep 100

Made it executable: chmod +x hello.sh and ran it:

./hello.sh &

I tried to see if I can find the process using ps and grepping for the name of the process, but it did not show up.

ps -ef | grep hello

Then I did the same but this time grepping for the process ID. (That's why I printed it in my experimental script.)

ps -ef | grep 12345

This time I saw the process and the name of the process was -bash.

sh-bang line

Usually in Linux/Unix the first line of each script should point to the command that will be able to interpret the code in the file. It is called sh-bang.

I've added it to the script (and renamed it becasue the web site can only have one file with the same name):

examples/shell/hello_again.sh

#!/bin/bash

echo $$
sleep 100

Making this executable: chmod +x hello_again.sh and runing this the same way: ./hello_again.sh. This time the full name showed up in the output of ps.

Running with bash

I tried also running it with bash like this:

bash hello_again.sh

On Ubuntu it seems it showd up with the full name, but as I recall in CentOS it had the same result as the first version, showing up only as -bash.