if file exists

1, determine whether the file exists, does not exist to create a file[Java]View Plaincopyprint? File file=new file ("c:\\users\\qping\\desktop\\javascript\\2.htm"); if (!file.exists ()) { try { File.createnewfile (); } catch

Test Condition Expression Description File symbols: [Root@lamp test]# Help testtest:test [expr]Evaluate conditional expression.Exits with a status of 0 (True) or 1 (false) depending onThe evaluation of EXPR.  Expressions May is unary or binary.

Conditional expression ("CONDITIONAL EXPRESSIONS") Conditional expressions are used in [composite commands and built-in command test and [to test file properties for string and arithmetic comparisons.] An expression is constructed using the

$ () and "(anti-quote ) are used to do command substitution. Next, let's see ${} ... It's actually used for variable substitution. Shell if interpretation statements are common:[Front and rear spaces] Front Space[-D file] True if file exists and

Objective:No matter what programming language is inseparable from conditional judgment. The shell is no exception.Copy CodeThe code is as follows:If List ThenDo something hereElif List ThenDo another thing hereElseDo something else hereFiEX1:Copy

Writing the first shell scriptLike other languages, we use any kind of text editor, such as Nedit, Kedit, emacs, vi, etc. to write our shell program. The program must start with the following line (must be in the first line of the file):#!/bin/shThe

Shell condition judgmentIf List ThenDo something hereElif List ThenDo another thing hereElseDo something else hereFiEX1:#!/bin/shSystem= ' uname-s ' #获取操作系统类型, I'm local Linuxif [$SYSTEM = "Linux"]; Then #如果是linux的话打印linux字符串echo "Linux"elif

1. string Judgments STR1 = str2 True when two strings have the same content, length Str1! = str2 True when strings str1 and str2 are unequal -N str1 True when the length of a string is

Xi. functionsThe shell function is defined by the description of the shell grammar above and holds a series of commands waiting to be executed later. When the shell function name is used as a simple command name, a series of commands associated with

[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if file exists and is a directory.[-E File] True if file exists.[-F file] True if file

[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if file exists and is a directory.[-E File] True if file exists.[-F file] True if file

[ -a file] is true if file exists. [ -b file] True if file exists and is a block special file. [ -c file] True if file exists and is a word special. [ -d file] True if file exists and is a directory. [ -e file] is true if file exists. [ -f file]

Recently scripting, I often see conditional statements with the IF [-X $variable] class, not knowing what the meaning of the corresponding parameter is,The excerpt is as follows: from http://blog.csdn.net/aaaaatiger/article/details/1713611thanks!1[ -

[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if file exists and is a directory.[-E File] True if file exists.[-F file] True if file

If statement format:If condition then statements [elif condition then statements ...] [Else statements] fiThe syntax for the most streamlined if command is:if TEST-COMMANDS; then CONSEQUENT-COMMANDS; fiThe IF condition judgment statement

This article mainly introduced the shell script if condition judgment and the judgment condition summary, this article first gave the IF condition judgment the grammar, then gave the commonly used judgment condition summary, needs Friend can refer

The shell condition determines if the-Z to-D meaningShellfilestringless Terminal user[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if

From: http://m.jb51.net/article/56553.htm This article mainly introduced the shell script if condition judgment and the judgment condition summary, this article first gave the IF condition judgment the grammar, then gave the commonly used judgment

[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if file exists and is a directory.[-E File] True if file exists.[-F file] True if file

by Francis_hao Oct 1,2017This article extracts the Man Handbook from bashConditional expressionsThe conditional expression is composed of a composite command [[or] built-in command test and [used for testing file properties and string or numeric