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Linux lsattr chattr I was trying to remove an old file from my computer but for some reason was unable to delete it. When I tried to remove it I got the message “rm: cannot unlink ‘filename’: Operation not permitted” I was logged in as root when I tried this command – again unable to […]

Using awk to filter specific information. # print column one using space as a separator grep /var/log/maillog.1 | awk ‘{print $1}’ # print column four using : as a separator grep /var/log/maillog.1 | awk -F “:” ‘{print $4}’ Use grep -i for case insensitive search.

How to obtain a new root.cache / root.hints file Download via ftp: wget -O named.cache ftp://ftp.internic.net/domain/named.cache Or: Use dig to download records from root server. dig @198.41.0.4 > root.cache Note: Using dig does not seem to get IPV6 records.

How to remove duplicate packages in rpm rpm -e –allmatches mysql –nodeps Note: This also uninstalls the package(s).

Linux library info ldd `which smbd` | grep cups e.g. # ldd `which smbd` | grep cups libcups.so.2 => /usr/lib/libcups.so.2 (0x00f76000) # ldd `which perl` | grep perl libperl.so => /usr/lib/perl5/5.8.5/i386-linux-thread-multi/CORE/libperl.so (0x00994000)

Setting Linux date. Go back 1 hour date –set=’-60 minutes’ Go forward 4 months date –set=’+4 months’ Go back 2 days date –set=’-2 days’

Removing ^M from Unix files with vi Description – UNIX treats the end of line differently than other operating systems. Sometimes when editing files in both Windows and UNIX environments, a CTRL-M character is visibly displayed at the end of each line as ^M in vi. Directions – To remove the ^M characters at the […]

This example shows how to create a custom xinetd service, in this case to forward radmin (port 4899) to another server using netcat. Create a file in /etc/sysconfig/xinetd.d/ (call it what you want – but for this example radmin would be a good choice) Create a definition in your /etc/services file contains a mapping for […]

Turn on IP forwarding in Linux IP. To turn forwarding on temporarily, use the following command as root: (this will be disabled after a reboot) echo “1” > /proc/sys/net/ipv4/ip_forward Or to make it permanent add the following to /etc/sysctl.conf net.ipv4.ip_forward = 1 In older versions of Redhat / CentOS you can edit /etc/sysconfig/network and enable […]

Label Linux partitions e2label device e2label /dev/sda1