[SOLVED] root gets 'permissions denied'

seog · 03-05-2020, 10:48 AM

5 years ago the like thread was marked as solved yet can't help me now.
after my desk top switched off on his own I decided to find out what 'syslog' was about maybe it can tell me why it happened.

Code:

root@debian:~# /var/log/syslog
bash: /var/log/syslog: Permission denied
root@debian:~# id
uid=0(root) gid=0(root) groups=0(root)
root@debian:~# grep :0: /etc/passwd
root:x:0:0:root:/root:/bin/bash

oops!

Code:

root@debian:~# whoami
root
root@debian:~# /var/log/syslog
bash: /var/log/syslog: Permission denied

damn!
it's time to consult clever people and here am I. help, please!

TenTenths · 03-05-2020, 10:52 AM

Quote:

Originally Posted by seog

Code:

root@debian:~# /var/log/syslog
bash: /var/log/syslog: Permission denied

damn!
it's time to consult clever people and here am I. help, please!

Why are you trying to execute /var/log/syslog?

hazel · 03-05-2020, 11:45 AM

If you want to read any kind of log, you must pass it to a command for reading text. The ones most often used for this purpose are more and less. I prefer less because it allows you to go backwards as well as forwards.

If you just type "/var/log", the shell will think you want to execute this file as a program. It will try to do that and will fail because text files are not programs and don't have the execute bit set. Not even root can turn a text file into an executable program!

scasey · 03-05-2020, 11:50 AM

Quote:

Originally Posted by hazel

If you want to read any kind of log, you must pass it to a command for reading text. The ones most often used for this purpose are more and less. I prefer less because it allows you to go backwards as well as forwards.

Hmmm. In more, typing a 'b' pages backwards (and '/' can be used to enter a search term, but that only searches forwards)
At least, that's how it works for me.

hazel · 03-05-2020, 11:54 AM

Quote:

Originally Posted by scasey

Hmmm. In more, typing a 'b' pages backwards (and '/' can be used to enter a search term, but that only searches forwards)
At least, that's how it works for me.

Amazing! You learn something every day. I've been using Linux for 20 years now and I didn't know you could go backwards in more. Maybe I ought to read the man page

ehartman · 03-05-2020, 01:01 PM

Quote:

Originally Posted by scasey

Hmmm. In more, typing a 'b' pages backwards

That, of course, depends on which more your distro/system has installed.
The original Unix (BSD) more could only go forward (show "more" of the file).
That's why the less and most commands were written.

From the man page for the more from "util-linux" (a GNU package):

Quote:

This version is especially primitive. Users should realize that less(1) provides more(1) emulation plus extensive enhancements.

This version does provides the 'b' or 'ctrl-B' commands, though.

seog · 03-05-2020, 11:40 PM

Quote:

Originally Posted by TenTenths

Why are you trying to execute /var/log/syslog?

dear TenTenth, as I mentioned in the original post the desk top started to switch off when I don't ask it for it.

yours`
sehrguey

seog · 03-05-2020, 11:55 PM

Quote:

Originally Posted by hazel

If you want to read any kind of log, you must pass it to a command for reading text. The ones most often used for this purpose are more and less. I prefer less because it allows you to go backwards as well as forwards.

If you just type "/var/log", the shell will think you want to execute this file as a program. It will try to do that and will fail because text files are not programs and don't have the execute bit set. Not even root can turn a text file into an executable program!

dear hazel
it was the first time ever I tried to look so deep under the hood and a couple of blogs/tutorials never mentioned '/var/log'
to be used as argument to 'less' or 'more' I wasn't overly tired and emotional to miss such a point.
Anyway, the problem mentioned in the thread heading is solved and you're my hero today.
yours`
sehrguey

scasey · 03-05-2020, 11:56 PM

seog, I'm sorry we haven't made this clear...
To see what's in /var/log/syslog, you need to

Code:

more /var/log/syslog
#or
less /var/log/syslog

Let us know what you see there about your "desktop switching off"

seog · 03-06-2020, 11:53 PM

Quote:

Originally Posted by scasey

seog, I'm sorry we haven't made this clear...
To see what's in /var/log/syslog, you need to

Code:

more /var/log/syslog
#or
less /var/log/syslog

Let us know what you see there about your "desktop switching off"

dear scasey,
the answers to this thread participants made me think

Code:

less /var/log/syslog

was more preferable.
With the 'switching off' being somewhat off the subject I marked the thread as solved.
Now, by 'switching off' I mean being thrown out of the current session or even sudden complete inexplicable power off of the desk top that sometimes happens and exasperates me. Sadly, /var/log/syslog didn't make me any wiser, I fell into an ocean of messages I couldn't understand.
Thank you for asking.
yours`
sehrguey

hazel · 03-07-2020, 08:36 AM

Quote:

Originally Posted by seog

Sadly, /var/log/syslog didn't make me any wiser, I fell into an ocean of messages I couldn't understand.

If syslog does contain any useful information (and that is by no means certain; it's just the obvious place to start looking), then it will be at the end of the session that crashed. So when you next boot, look for the first entry that contains the current date and time. You can do that within either more or less by entering a / and then the string you are looking for. For example /Mar 7 14:03. Note the spacing: the day of the month occupies two columns. The immediately preceding lines will be the end of the last session. Possibly those lines will be of some use.

Depending on your distro, /var/log/ may also contain a separate kernel log (often called kern.log) and/or a combined messages file. All of these can be quickly checked in the same way. Look for messages that are actually flagged up as errors or warnings.

scasey · 03-07-2020, 01:34 PM

To add to what hazel said: When I'm looking to troubleshoot something, I often do an

Code:

ls -ltr /var/log

to identify which log file(s) was last written to right after the problem occurred.

seog · 03-07-2020, 11:25 PM

dear hazel and scasey,
thank you ever so much for the tools enabling me to start a threat with a more appropriate subject headline.
yours`
sehrguey