Linux What is umask (user mask) for file and directory creation permissions and how to calculate umask and change the defaults

umask are the default permissions that are applied when a file or directory are created. To see this in action simply just "touch filename" or "mkdir somedir" and you'll see what default permissions are applied. The first thing I always tell people you should know is to NEVER change the defaults unless you are making them more restrictive. But they work well and if you change the defaults you could end up creating a file without permission to read........

Linux Permissions and Groups Real Usecase for Group Access

I have a directory structure which the primary user needs full access on but wanted a user to access only a specific directory within the main directory (so they could write in there only and nowhere else). Here's what I did: [root@compevo8001 dllnow]# ls -alh drwxrwxr-x 2 someuser software 4.0K Oct 19 2017 ExpireYMD-2017-11-20 drwxrwxr-x 2 someuser software 4.0K Nov 19 2017 ExpireYMD-20........

gvfs mount in /run/user cannot be accessed or displayed wrong permissions

The folder contents could not be displayed Backend currently unmounting drwx------ 10 userhere group 260 Aug 23 19:40 .. ?????????? ? ? ? ? ? sftp:host=192.168.8.80,user=adhoc ls: cannot access 'sftp:host=192.168.8.80,user=adoc': Input/output error $ ps aux|grep fuse one 253........

Debian Mint Ubuntu compiling xmr-stak

sudo apt-get install libcurl4-openssl-dev git build-essential autotools-dev autoconf libcurl3 sudo apt-get install libcurl4-gnutls-dev git clone https://github.com/wolf9466/cpuminer-multi sudo apt-get install cmake libpthread-* libmicrohttpd-dev libssl-dev libhwloc-dev git clone https://github.com/fireice-uk/xmr-stak-cpu.git make install cd bin chmod +x xmr-stak-cpu ./xmr-stak -O xmr........

mysqld in Linux hacked

Check for crap in /var/lib/mysql like this ls -al /var/lib/mysql/ total 20888 drwxr-xr-x 24 mysql mysql 4096 Oct 3 18:30 . drwxr-xr-x 20 root root 4096 Oct 3 04:23 .. -rw-rw-rw- 1 mysql mysql 11776 Oct 3 17:10 c:exp.exe -rw-rw-rw- 1 mysql mysql 48128 Oct 3 17:10 c:exp1.exe........

ffmpeg trouble concatenating similar but different files

When things go wrong your video is basically unplayable or the first video plays fine and then freezes when moving on to the next. Generally if both videos weren't produced with the exact 100% same settings you will have issues. You can try the basic concat but it often won't work right. Solution for me: My example uses 3 videos in total so "n=3" and a=1 to include audio. ffmpeg -threads 12 -i file1.mp4 -........

ffmpeg Linux Mint download, compile and install howto

#if you have nvidia make sure you install the nvidia-cuda-toolkit so hardware acceleration can be used wget http://ffmpeg.org/releases/ffmpeg-3.3.2.tar.bz2 tar -jxvf ffmpeg-3.3.2.tar.bz2 cd ffmpeg-3.3.2/ ./configure --disable-yasm install prefix /usr/local source path ........

Centos 7 Cudaminer Nvidia setup guide

I am using a GTX 1060 but replace the download for the driver with the correct/current version for your particular card by visiting: http://www.nvidia.com/Download/index.aspx?lang=en-us yum install automake curl openssl-devel libcurl-devel gcc gcc-c++ yum -y install kernel-devel-`uname -r` yum -y install unzip #the........

Nvidia Linux Mint/Ubuntu screentearing horizontal line solution

Finally after ages I found the solution which is on many pages on the net but not obvious and should have been standard or more common info! Instant Solution: Type this into the terminal (unfortunately the driver config menu doesn't have the option as itis hidden): nvidia-settings --assign CurrentMetaMode="nvidia-auto-select +0+0 { ForceCompositionPipeline = On }" Make permanent Cli........

check if Apache uses worker MPM or prefork MPM

apachectl -l Compiled in modules: core.c prefork.c http_core.c mod_so.c It is "prefork.c" so in httpd.conf these settings are what you would use (if you use worker.c it won't have any impact): <IfModule prefork.c> StartServers 2 MinSpareServers 5 MaxSpareServers&nb........

grubby fatal error: unable to find a suitable template solution Centos

vzkernel-2.6.32-042stab116.2.x86_64.rpm &n........

Installing zoneminder on Ubuntu/Debian Linux Howto

sudo apt-get install zoneminder [sudo] password for one: Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: libuser-perl python-evince kdebase-apps kwrite unixodbc libgnomeprint2.2-data python-soappy vgabios python-metacity hddtemp python-mediaprof........

Vbox/Virtualbox devices grayed out for non-root user solution

It is a permissions issue that is hard to fix. All but one USB device is greyed out. I am already a member of "vboxusers" <ul> <li>I have already enabled and disabled USB support for the guest.</li> <li>I have already reinstalled the latest VBOx guest editions</li> <li>If running as root it all works fine</li> <li>Changing........

OpenVZ mismatched kernel and dev when compiling.

./configure ./configure: line 91: cd: /lib/modules/2.6.32-042stab084.25/build: No such file or directory Error: kernel version not found. Please make sure your kernel is configured. dr-xr-xr-x. 4 root root 4096 Feb 21 06:13 .. lrwxrwxrwx 1 root root 45 Feb 21 06:13 build -> ../../../usr/src/kernels/2.6.32-042stab084.25 drwxr-xr-x 2 root root 4096 Feb 12 20........

Asterisk iptables block bruteforce attacks howto with fail2ban

yum -y install fail2ban vi /etc/fail2ban/jail.conf [asterisk-tcp] enabled = true filter = asterisk action = iptables-multiport[name=asterisk-tcp, port="5060,5061", protocol=tcp] sendmail-whois[name=Asterisk, dest=you@example.com, sender=fail2ban@example.com] logpath = /var/log/asterisk/messages maxret........

Dell Perc 6/i cannot downgrade

I flashed an LSI Logic firmware to it and it broke the BIOS (cannot do Ctrl+R) for booting purposes but allows other functionality to work normally. I tried downgrading to a Dell firmware for Perc 6i but it won't work, not even with MegaCli wget http://downloads.dell.com/FOLDER00416606M/1/SAS-RAID_Firmware_W83M2_LN32_6.3.1-0003_A14.BIN --2013-08-26 12:53:39-- http://downloads.dell.com/FOLDER00416606M/1/SAS-RAID_Firmware_W83M2_LN32_6.3.1-0003_A14.BIN Resolvi........

vnstat setup guide/tutorial

yum -y install vnstat chown nobody.nobody -R /var/lib/vnstat/ #replace venet0 below with your desired interface sudo -u nobody vnstat -u -i venet0 #edit: vi /etc/sysconfig/vnstat #VNSTAT_OPTIONS="-i venet0" # only use the sed below if you are using venet0 instead of eth0 or replace accordingly sed -i 's/eth0/venet0/g' /etc/sysconfig/vnstat [root@monitor]# yum install vn........

Apache MPM worker vs prefork

find what MPM Apache is using, it will either be using "worker" or "prefork" apachectl -l Compiled in modules: core.c prefork.c http_core.c mod_so.c In my case it is "prefork" vi /etc/httpd/conf/httpd.conf Find the section that looks like this (by default one will normally exist for prefork and for worker, but in my case I only care a........

PHP cannot access /usr/bin/openssl

PHP cannot access /usr/bin/opensslI have verified the username that runs the process is able to access /usr/bin/openssl and it does exist but the PHP script is saying it doesn't exist: [code:1:1fd0f3abbe] if (!file_exists($OPENSSL)) { //echo "ERROR: OPENSSL $OPENSSL not foundn"; }[/code:1:1fd0f3abbe] I don't get itI can clearly see the contents of /usr/bin by using the PHP system fu........

Centos 4.3 x64 & VMWare Server Beta

Centos 4.3 x64 & VMWare Server Beta[code:1:6d0b2c8c2f] The correct version of one or more libraries needed to run VMware Server may be missing. This is the output of ldd /usr/bin/vmware: linux-gate.so.1 => (0xffffe000) libm.so.6 => /lib/tls/libm.so.6 (0xf7fbd000) libdl.so.2 => /lib/libdl.so.2 (0xf7fb9000) libpthread.so.0 => /lib/tls/libpthread.so.0 (0xf7fa7000) libX11.so.6 => not f........

Timezone Change/Updated for Linux/Unix Debian/Fedora/Ubuntu/Centos Change Update Time zone

This way should work on all Linux machines, at least RHEL/Debian (Ubuntu) based distros but most likely all and also should work on many Unix style machines I believe. Many OS's have tools to update the timezone, but most of them (even if command line) require several bloated packages and even Xorg/KDE based packages etc.. Your time zone info file is actually in /etc/localtime if you open this file in vi/vim/pico you'll see it's gibberish (binary code or another encodin........