Ημερήσια αρχεία: 28 Σεπτεμβρίου 2011

One line infinite while loop

 στο Bash / GNU/Linux / HowTos  επισημασμένο με ετικέτα bash / GNU/Linux / howtos / infinite / one line / oneliner / while loop Από 

while true; do echo 'Hit CTRL+C to exit'; someCommand; someOtherCommand; sleep 1; done

alternative syntax

while :; do echo 'Hit CTRL+C to exit'; someCommand; someOtherCommand; sleep 1; done

Include more filetypes to a WordPress Installation Media Library

 στο Applications / CMS / HowTos  επισημασμένο με ετικέτα applications / cms / filetype / howtos / media library / wordpress Από

In the folder <Installation Path>/wp-includes/ there is a file called functions.php, inside this file there is a function called get_allowed_mime_types().
This function is in charge of defining an Array of mime types keyed by the file extension with a regex corresponding to those types.

So in order to add a new file-type to the white-list you just have to add a new line with the following format in the list:

'jpg|jpeg|jpe' => 'image/jpeg',

Where, on the left you define the extensions you want to be accepted separated by the vertical bar character (“|”) and on the right you give a file definition.

Bash: Read a file, line by line

 στο Bash / GNU/Linux / HowTos  επισημασμένο με ετικέτα bash / count / exec / GNU/Linux / howtos / line Από

The following script will accept from the keyboard a filename, later it will read it and process it line by line.
In this example we will just number the lines, print them and count the total number of lines in the file.

#!/bin/sh
echo Enter the Filename to process
read filename
exec<$filename
lineNumber=0
while read line
do
	lineNumber=`expr $lineNumber + 1`;
	echo $lineNumber - $line;
done
echo "Total Lines Number: $lineNumber";

Remove leading characters/information from line using sed

 στο Bash / GNU/Linux / HowTos  επισημασμένο με ετικέτα bash / GNU/Linux / howtos / leading space / prefix / remove / sed Από

Remove leading numbering from line

We had these log files that on most lines at the beginning there was a number followed by a dot and some times it had space characters.
The following sed command removes that prefix. and leaved intact the rest of the lines that do not have the prefix.

cat $log | sed '/^[0-9]*. */!d; s///;q';

e.g

Input: 123. Some text here.
Output:Some text here.

Remove leading whitespace (space and tabs) from line:

The following sed script will remove all leading whitespace from each line by using a regular expression to match space characters and tabs.

cat $log | sed 's/^[ t]*//';

e.g

Input:       Some text here.
Output:Some text here.