$ sudo &gt; syslog  -bash: syslog: Permission denied  $ ls -la syslog  -rw-r----- 1 syslog adm 11673034092 2016-09-01 16:55 syslog   What's going on here?
804
When using sudo to allow edits to files, I regularly get 'permission denied'.  For example, my mouse is jittery and sluggish, so I want to disable polling:  sudo echo "options drm_kms_helper poll=N"&gt;/etc/modprobe.d/local.conf   I'm prompted for a password, and then get:  bash: /etc/modprobe.d/local.conf: Permission denied   So I tried to do a temporary change to disable polling by using:  sudo echo N&gt; /sys/module/drm_kms_helper/parameters/poll   Yet again the system responded with:  bash: /sys/module/drm_kms_helper/parameters/poll: Permission denied   Any ideas?
14415
I have a small server which I use for testing and programming. Currently it runs Debian 9.4 stretch with 4.14.0-0.bpo.3-amd64 kernel.  Today I tried to connect through SSH but I couldn't then I tried to ping it and it was unreachable. Therefore I had to hard-restart it by unplugging power cable. Then I went to  /var/log/syslog  and I found a strange line containing exactly 6140 characters like the following  ^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@  then nothing else until new log entries of system restart. This is actually the first time it happens.  Does someone know what could it be?
13810
Using ps -aux or top, I can list other users running processes, but I'm neither running as root nor making use of sudo, why?
113805
Recently back to Linux from another operating system I noticed a file called [ which seems strange to me.  What is it for?  $ ls -l /usr/bin | head -2 -rwxr-xr-x 1 root root       39552 Nov  3 14:44 [   I'm using Ubuntu 15.04
98077
$ sudo -iu abc ls -ltr /sites/servers/server_instance/logs/access* ls: cannot access /sites/servers/server_instance/logs/access*: No such file or directory  $ sudo -iu abc ls -ltr /sites/servers/server_instance/logs/ total 594812 -rwxrwxrwx 1 abc abc      45 Mar 21 12:42 old.log -rwxrwxrwx 1 abc abc      304537970 Mar 24 12:45 console.log -rwxrwxrwx 1 abc abc      304537970 Mar 24 13:20 access_nginx.log   Can anyone explain why this happens? I am stuck on a script due to this.
32331
I've connected a USB to Serial bridge dongle, and running dmesg | grep tty outputted the following:  [    0.000000] console [tty0] enabled [603199.380677] usb 2-2: cp210x converter now attached to ttyUSB0   So now I'm trying to write to it as per  by running the following:  cat hello.txt &gt; /dev/ttyUSB0   and   sudo cat hello.txt &gt; /dev/ttyUSB0   But both result in the following error:  bash: /dev/ttyUSB0: Permission denied   What am I doing wrong?  Thanks
9397
I'm only granting permission to all to do anything but why does the system crash by giving permissions only? I'm only modifying the permission not changing the files.
80757
How does sudo work internally? How is it possible that it can become root without having the root password, unlike su? What syscalls, etc. are involved in the process? Is it not a gaping security hole in Linux (e.g. why couldn't I compile a heavily-patched sudo that just did whatever regular sudo did, but didn't ask for the unprivileged user's password)?  I have read . I have also read  but despite the title, they mainly deal with the differences between su and sudo.
34426
This seems very strange to me. I'm running kernel 2.6.37.2 and ran:  ~]$ cp -r /proc/ here ~]$ rm -rf here   I get some permission denies when copying as expected and I eventually hit Control-C. I get Permission denied on a lot of files when trying to remove the new directory and files.  As a note, I found this weird behavior because a friend sent me a .tgz of a snapshot of his /proc dir. I extracted the directory and when I was finished looking through it I had the same problem.  rm -rf as root does work.  lsattr shows the e attribute (which is what all of my files/directories show).
4367
This is a pretty simple question, at least it seems like it should be, about sudo permissions in Linux.  There are a lot of times when I just want to append something to /etc/hosts or a similar file but end up not being able to because both &gt; and &gt;&gt; are not allowed, even with root.  Is there someway to make this work without having to su or sudo su into root?
99605
[root@notebook ~]# grep root /etc/sudoers root    ALL=(ALL)   ALL   Question: Why does the root user need sudo permissions? I've seen it on different UNIX OSes. Can someone please explain this?
3555
My syslog file is has large number almost continuous entries as follows.  Apr 13 11:49:40 nrao-XPS-8700 gnome-session[2439]: Memory pressure relief: Total: res = 9682944/9682944/0, res+swap = 0/0/0 Apr 13 11:50:05 nrao-XPS-8700 gnome-session[2439]: Memory pressure relief: Total: res = 12369920/12369920/0, res+swap = 0/0/0 Apr 13 11:50:07 nrao-XPS-8700 gnome-session[2439]: Memory pressure relief: Total: res = 10633216/10690560/57344, res+swap = 0/0/0 Apr 13 11:50:10 nrao-XPS-8700 gnome-session[2439]: Memory pressure relief: Total: res = 9682944/11800576/2117632, res+swap = 0/0/0 Apr 13 11:50:35 nrao-XPS-8700 gnome-session[2439]: Memory pressure relief: Total: res = 12369920/12369920/0, res+swap = 0/0/0   Output of free -m command is follows                total        used        free      shared  buff/cache     available Mem:          15998        7155        5903         113        2939        8323 Swap:         18477        4182       14295
31056
I've accidentally run this command  sudo mv /* /applications/minced/   instead of   sudo mv ./* /applications/minced/   This is all that's left in the root directory  $ / applications/ dev/          proc/         run/          sys/          tmp/          I still have an active ssh connection to the server. I've tried calling mv, sudo and chmod... directly from /applications/minced/bin/ or /applications/minced/usr/bin/, but nothing works, though I can locate them there using path autocompletion.   $ /applications/minced/bin/ls -bash: /applications/minced/bin/ls: No such file or directory   I've read , but mounting the system under LiveCD is not an option for me since it's a VPS, not a physical machine. Any ideas?  Update  I figured out this is due to library linkage problems, so I did this   $ export LD_LIBRARY_PATH=/applications/minced/lib/x86_64-linux-gnu/ $ /applications/minced/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 /applications/minced/bin/mv /applications/minced/* /   Obviously I ran into permission problems. Calling sudo with the linker throws this error  $ /applications/minced/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 /applications/minced/usr/bin/sudo ... sudo: effective uid is not 0, is /applications/minced/usr/bin/sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges?   As suggested by Barafu Albino, I've tried calling su with busybox (.../bin/busybox su -), but it throws su: must be suid to work properly. I guess this happens because su can't locate /etc/passwd and /etc/shadow. Seems like I've screwed up the system completely.
94820
Symbolic link not working, using standard UBUNTU 16 LTS... It shows "Permission denied" where I expected to get access, not working even after chown.  Full example:  sudo rm /tmp/file.txt  # if exist, remove  cd ~ sudo chmod 666 data/file.txt ls -l data/file.txt    # "-rw-rw-rw-" as expected more data/file.txt     # working fine sudo ln -sf $PWD/data/file.txt /tmp/file.txt  # fine ls -l /tmp/file.txt    # "lrwxrwxrwx",  /tmp/file.txt -&gt; /home/thisUser/file.txt more /tmp/file.txt     # fine  sudo chown -h postgres:postgres /tmp/file.txt  sudo more /tmp/file.txt   #  NOT WORK! but its is sudo! and 666!
8780
This is a  about File Permission and Why 777 is "destructive".   I'm not asking how to fix this problem, as there are a ton of references of that already on Server Fault (reinstall OS). Why does it do anything destructive at all?  If you've ever ran this command you pretty much immediately destroy your operating system. I'm not clear why removing restrictions has any impact on existing processes. For example, if I don't have read access to something and after a quick mistype in the terminal suddenly I now have access well... why does that cause Linux to break?
2744
( deals with a similar issue, but it talks about a rotated log file.)  Today I got a system message regarding very low /var space.   As usual I executed the commands in the line of sudo apt-get clean which improved the scenario only slightly. Then I deleted the rotated log files which again provided very little improvement.  Upon examination I find that some log files in the /var/log has grown up to be very huge ones. To be specific, ls -lSh /var/log gives,   total 28G -rw-r----- 1 syslog            adm      14G Aug 23 21:56 kern.log -rw-r----- 1 syslog            adm      14G Aug 23 21:56 syslog -rw-rw-r-- 1 root              utmp    390K Aug 23 21:47 wtmp -rw-r--r-- 1 root              root    287K Aug 23 21:42 dpkg.log -rw-rw-r-- 1 root              utmp    287K Aug 23 20:43 lastlog    As we can see, the first two are the offending ones. I am mildly surprised why such large files have not been rotated.  So, what should I do? Simply delete these files and then reboot? Or go for some more prudent steps?  I am using Ubuntu 14.04.  UPDATE 1  To begin with, the system is only several months old. I had to install the system from scratch couple of months back after a hard disk crash.  Now, as advised in ,  I first checked the offending log files using tail, no surprise there. Then, for deeper inspection, I executed this script from the .  for log in /var/log/{syslog,kern.log}; do    echo "${log} :"   sed -e 's/\[[^]]\+\]//' -e 's/.*[0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}//' ${log} \   | sort | uniq -c | sort -hr | head -10 done   The process took several hours.  The output was in the line of,   /var/log/syslog : 71209229  Rafid-Hamiz-Dell kernel:  sda3: rw=1, want=7638104968240336200, limit=1681522688 53929977  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device 17280298  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device    1639  Rafid-Hamiz-Dell kernel:  EXT4-fs warning (device sda3): ext4_end_bio:317: I/O error -5 writing to inode 6819258 (offset 0 size 4096 starting block 54763121030042024)        &lt;snipped&gt;  /var/log/kern.log.1 : 71210257  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device 71209212  Rafid-Hamiz-Dell kernel:  sda3: rw=1, want=7638104968240336200, limit=1681522688    1639  Rafid-Hamiz-Dell kernel:  EXT4-fs warning (device sda3): ext4_end_bio:317: I/O error -5 writing to inode 6819258 (offset 0 size 4096 starting block 954763121030042024)    (/dev/sda3 is  my home directory. As we can find,   lsblk /dev/sda NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT sda      8:0    0 931.5G  0 disk  ├─sda1   8:1    0 122.1G  0 part / ├─sda2   8:2    0   7.6G  0 part [SWAP] └─sda3   8:3    0 801.8G  0 part /home    Why a process will want to write beyond the limit is actually outside the scope of my comprehension. Perhaps I will want to ask a different question in this forum if this continues even after a system update.)  Then, from  (you may want to check  for a deeper understanding), I executed,   sudo su - &gt; kern.log &gt; syslog   Now, these files have zero sizes. The system is running fine before and after a reboot.   I will watch these files (along with others) in the next few days and report back should they behave out-of-line.  As a final note, both  the offending files (kern.log and syslog), are set to be rotated, as inspection of the files (grep helped) inside  /etc/logrotate.d/ shows.  UPDATE 2  The log files are actually rotated. Looks like the large sizes were attained on a single day.
37777
From  we learn that in order for Bash to perform auto-completion one must perform . /etc/etc/bash_completion.d/foobar (note the space after .) in order for Bash completion to work.  $ /etc/bash_completion.d/ssh bash: /etc/bash_completion.d/ssh: Permission denied $ . /etc/bash_completion.d/ssh $ ls -l /etc/bash_completion.d | grep ssh -rw-r--r-- 1 root root   297 Jan 28 18:04 ssh   Is . a shortcut for the source command? If not, then what is it? It is impossible to google for, man source returns nothing, and apropos source and info source give so much irrelevant information that I cannot tell if what I'm looking for is in there. How might I even begin to RTFM to find the answer to this question myself?