Code Samples: shell script

Sunday, August 25, 2013

HowTo Format Date For Display or Use In a Shell Script

How do I format date to display on screen on for my shell scripts as per my requirements on Linux or Unix like operating systemsYou need to use the standard date command to format date or time. You can use the same command with the shell script.
The syntax is

date +FORMAT
date +"%FORMAT"
date +"%FORMAT%FORMAT"
date +"%FORMAT-%FORMAT"

Task: Display date in mm-dd-yy format

Open a terminal and type the following date command:
$ date +"%m-%d-%y"Sample output:

02-27-07

To turn on 4 digit year display:
$ date +"%m-%d-%Y"Just display date as mm/dd/yy format:
$ date +"%D"

Task: Display time only

Type the following command:
$ date +"%T"Outputs:

19:55:04

To display locale's 12-hour clock time, enter:
$ date +"%r"Outputs:

07:56:05 PM

To display time in HH:MM format, type:
$ date +"%H-%M"Sample outputs:

00-50

How do I save time/date format to the shell variable?

$ NOW=$(date +"%m-%d-%Y"To display a variable use echo / printf command:
$ echo $NOW

A sample shell script

#!/bin/bash
NOW=$(date +"%m-%d-%Y")
FILE="backup.$NOW.tar.gz"
echo "Backing up data to /nas42/backup.$NOW.tar.gz file, please wait..."
# rest of script
# tar xcvf /nas42/backup.$NOW.tar.gz /home/ /etc/ /var

A complete list of FORMAT control characters supported by the date command

FORMAT controls the output. It can be the combination of any one of the following:

%FORMAT String	Description
%%	a literal %
%a	locale's abbreviated weekday name (e.g., Sun)
%A	locale's full weekday name (e.g., Sunday)
%b	locale's abbreviated month name (e.g., Jan)
%B	locale's full month name (e.g., January)
%c	locale's date and time (e.g., Thu Mar 3 23:05:25 2005)
%C	century; like %Y, except omit last two digits (e.g., 21)
%d	day of month (e.g, 01)
%D	date; same as %m/%d/%y
%e	day of month, space padded; same as %_d
%F	full date; same as %Y-%m-%d
%g	last two digits of year of ISO week number (see %G)
%G	year of ISO week number (see %V); normally useful only with %V
%h	same as %b
%H	hour (00..23)
%I	hour (01..12)
%j	day of year (001..366)
%k	hour ( 0..23)
%l	hour ( 1..12)
%m	month (01..12)
%M	minute (00..59)
%n	a newline
%N	nanoseconds (000000000..999999999)
%p	locale's equivalent of either AM or PM; blank if not known
%P	like %p, but lower case
%r	locale's 12-hour clock time (e.g., 11:11:04 PM)
%R	24-hour hour and minute; same as %H:%M
%s	seconds since 1970-01-01 00:00:00 UTC
%S	second (00..60)
%t	a tab
%T	time; same as %H:%M:%S
%u	day of week (1..7); 1 is Monday
%U	week number of year, with Sunday as first day of week (00..53)
%V	ISO week number, with Monday as first day of week (01..53)
%w	day of week (0..6); 0 is Sunday
%W	week number of year, with Monday as first day of week (00..53)
%x	locale's date representation (e.g., 12/31/99)
%X	locale's time representation (e.g., 23:13:48)
%y	last two digits of year (00..99)
%Y	year
%z	+hhmm numeric timezone (e.g., -0400)
%:z	+hh:mm numeric timezone (e.g., -04:00)
%::z	+hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z	numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z	alphabetic time zone abbreviation (e.g., EDT)

Execute shell commands in PHP

/**
Method to execute a command in the terminal
Uses :

1. system
2. passthru
3. exec
4. shell_exec

*/
function terminal($command)
{
    //system
    if (function_exists('system')) {
        ob_start();
        system($command, $return_var);
        $output = ob_get_contents();
        ob_end_clean();
    } //passthru
    else if (function_exists('passthru')) {
        ob_start();
        passthru($command, $return_var);
        $output = ob_get_contents();
        ob_end_clean();
    } //exec
    else if (function_exists('exec')) {
        exec($command, $output, $return_var);
        $output = implode("\n", $output);
    } //shell_exec
    else if (function_exists('shell_exec')) {
        $output = shell_exec($command);
    } else {
        $output = 'Command execution not possible on this system';
        $return_var = 1;
    }

    return array('output' => $output, 'status' => $return_var);
}

Use as this way:
$o = terminal('ls');
print_r($o);

http://www.binarytides.com/execute-shell-commands-php/

Saturday, November 24, 2012

Replace a string in file using shell script

Suppose my file a.conf is as following

Include /1
Include /2
Include /3

I want to replace "Include /2" with a new line, I write the code in .sh file :

line="Include \\/2"
rep=""

sed "s/${line}/${rep}/g" /root/new_scripts/a.conf > /tmp/a.conf-new

mv /tmp/a.conf-new /root/new_scripts/a.conf

Encrypt a file using bash shell script

openssl des3 -salt -in /pritom/input.sql -out /pritom/output.pk -pass pass:pritom

where:

 /pritom/input.sql is the input file

 /pritom/output.pk is encrypted output file

 -pass pass: pritom (pritom is used as password)

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