linux date arithmetic

Using date types in PL/SQLThe previous article described the use of strings and numbers in PL/SQL. There is no doubt that strings and numbers are important, but you can be sure that no application is dependent on the date.You need to record events,

A detailed description of the arithmetic operators for Bash programming under Linux (iii)The shell arithmetic operation is represented as follows:1. Let arithmetic operation expressionLet c= $A + $B2. $[arithmetic operation expression]c=$[$A + $B]3,

Bash working features:1. Support Command history, command completion2. Support Pipeline, redirect3. Support Command aliases4. Support for command line editing5. Support Command line deployment6. Support File name wildcard7. Support for using

Type of variable in bash Local variable: Valid only for the current shell and not for its child shell Variable assignment: Name=value Name= $user Name= ' command ', name=$ (command): "The Meaning of" and $ () is different. The following figure

Egrep and extended regular expressions, conditional expressions, and arithmetic operationsLinux05Linux05_01? Use and extend regular expressions in egrepREGEXP: REGular EXPression. It may not represent its own meaning, but it is used for special

Exercise: Write a scriptDetermine if there is a user's default shell for bash on the current system;If so, the number of such users is displayed, otherwise, no such user is shown;#!/bin/bash#grep '\'/etc/passwd&>/dev/NULLRETVAL=$?if[$RETVAL-eq0];

/*boost provides a timer and a data_time library for time and date processing * *The Timer library provides easy time-to-measure and progress-display features that can be used for tasks such as performance testing that require timing/*Timer of the

Command-linux the basis of learning, and the foundation is the core.???? There is no foundation but a castle in the ground, every time when dealing with problems, we need to ask outside the power, and lack of their ability to solve problems.????

1. Display timeThe date command displays dates in the specified format, and only date displays the current time in the default format. As follows:If you need to display the date in the specified format, you can use a string that begins with "+" to

The first-and mid-level Linux OPS personnel learn and quickly master Linux's operational combat skills. The Learning route outline is as follows: Introductory Basics System operation and Maintenance chapter Web operation and