Simple question, I thought...

Need to Single step/line-by-line through the CentOS-7.2-1511 boot process.

I did this way back in the RedHat 3/4/5 days but can't find my notes.

I understand searching before asking/posting :-)
I have, both here and elsewhere but most queries with the word
"single" come back 'boot single user mode' or 'boot root user'

As a tech I usually remove 'quiet' and 'rhgb' options from the vmlinuz line
in the grub.cfg file just to make sure I see what what is happpening
during the boot process.

This is a 'Power' Laptop booting CentOS-7.2-1511 and running WMware
WorkStation-12 to spin up Virt-Machines I need to work multiple
client environments.

Sometimes network connectivity can been 'spotty' at client sites.
Most times at most client sites
lines comeback [ Ok ]

but sometime at client sites during the 'network' portion
lines comebak [failed]

but blow by to fast to read...
and this is why I would like to single step through the process!


Any help/hint would be greatly appreciated
Thanks

At one time you could single step loading services by pressing Ctrl-A? at the right time in the boot process if I remember correctly. I don't remember if there was another method... You can go back through the systemd journal to find the error.

https://fedoramagazine.org/systemd-using-journal/
https://wiki.archlinux.org/index.php/systemd

Another example of xyproblem.
To save ploughing through the journal try "systemctl --state=failed"

Dear,
syg00

Pleases don't scold me.
You are not good enough to do so...

As stated in my opening remarks
I ALWAYS practice 'due diligence'.

Look back at my post...
"...understand searching before asking/posting..."

[mod remove content] Mod comment; Do not post in this manner since you will be and are violating LQ Rules

So ... reported.

My suggestion is not how to run single step (minus a debugger that is) but instead to modify the boot code to have printk() statements to aid in debugging it, however I didn't think it would be useful to you.

While syg00 was sarcastic, they were offering a different alternative. Still, being sarcastic was a bit harsh.

Reacting worse about it is definitely a lot harsh.

I am not scolding you but I know your original content violates LQ Rules. I suggest that you re-read LQ Rules and the following; http://www.linuxquestions.org/questi...#faq_lqwelcome So that you are aware of proper posting and not violating the LQ Rules.

My apologies to the community and syg00 all for my
language/attitude...

This was a Network Down Emergency. (Three time zones)
and the the Bat-Phone was ringing off the hook!


FYI...
While still not single step...
you can also trap boot messages to a file as follows
in two ways.


Append/Re-compile the Kernel
#####################################################
int main{
int newFile= open(desiredFilePath, O_WRONLY)
if ((fork())==0){
dup2(newFile,stdout) // Explained below
close newFile
Set stdout as CLOSE_ON_EXEC false
exec the user program
}else{
wait for child
}
return 0
}

##### And/Or #####



#include <stdio.h>
#include <unistd.h>

int main (int argc, char *argv[]) {
if (isatty (fileno (stdout)))
fprintf (stderr, "output goes to terminal\n");
else
fprintf (stderr, "output goes to file\n");

return 0;
}