USEFULL LINUX COMMANDS

Disk Usage and Disk Free Command
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df -h = free hard drive space
df = free hard drive space
du -sh = disk usage
du -h = hard drive usage

Change Permissions
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chmod o=rwx, g=rw, u=r /usr/local/bin = change file permissions
chmod ogu=rwx /usr/local/bin = change file permissions

Others
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cat /var/log/yum.log
cat /var/log/yum.log | grep mysql = mysql install and update dates
cat /proc/meminfo = prints memory info
cat /proc/cpuinfo = prints cpu info
cat /proc/devices = list of devices
cat /proc/stat = disk statictics
cat /proc/filesystems = file system info
cat /proc/interrupts = IRQ channel assignments
cat /proc/iomem = physical memory addresses
cat /etc/x11/xorg.conf = monitor info
cat -s filename.txt = shows consecutive blank lines as one
cat -n filename.txt = shows all lines with numbers
cat -b filename.txt = shows only none-blank lines with numbers
cat filename.txt | head = gives top 10 lines ie head of the file
cat filename1 filename2 > filename3 = merges the files
cat filename1 filename2 >> filename3 = adds contents to another files
cat /etc/fstab = list of all devices
cat /etc/filesystems = of file systems
cat /etc/fedora-release = Fedora release/version no
cat /etc/issue = Linux distro name
cat /var/log/messages | grep -F ntpd =
cat /var/log/wtmp = lists all logins and logouts
cat /run/utmp = lists last reboots and shutdowns
cat /bin/ls | strings = lists all ASCII text in ls