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Remove a line from a file using sed (useful for updating known SSH server keys when they change)
For example, to remove line 5 from foo, type: vi +5d +wq foo

return a titlecased version of the string
Needs Bash4. Found at http://stackoverflow.com/questions/2264428/converting-string-to-lower-case-in-bash-shell-scripting alongside a few other tricks.

AWK command to extract log files between dates

Testing php configuration

generate random ascii shape(no x11 needed!)

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Migrate existing Ext3 filesystems to Ext4
Before doing this, back-up all data on any ext3 partitions that are to be converted to ext4. After running previous command you MUST run fsck, is needed to return the filesystem to a consistent state. $ fsck -pDf /dev/yourpartition Edit /etc/fstab and change the 'type' from ext3 to ext4 for any partitions that are converted to ext4.

Averaging columns of numbers
This example calculates the averages of column one and column two of "file.dat". It can be easily modified if other columns are to be averaged.

Runs a command without hangups.
The improvement is that you can re-attach to the screen at a later point.

recursive search and replace old with new string, inside files
recursively traverse the directory structure from . down, look for string "oldstring" in all files, and replace it with "newstring", wherever found also: $ grep -rl oldstring . |xargs perl -pi~ -e 's/oldstring/newstring'


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