The cat command return zero(0) i.e. exit status, on successful, this can be used, in if condition as follows, Write shell script as $ cat > showfile #!/bin/sh # #Script to print file # if cat $1 then echo -e "\n\nFile $1, found and successfully echoed" fi if-than-else-...
1)echo命令输出结果-e 格式控制字符:\c \t \n2)read命令读取信息3)文件重定向 command>filename command>>filename [追加] command1>filename command> filename2>&1command2>filename command2>>filename command>> filename2>&1command< filename >filename2 command< filename 7. 引号使用 双引号""单...
3、学习条件测试语句。在 Shell 脚本中，有一部分测试是整数之间的比较，也有一部分测试是字符串的匹配。
Chapter 21. Shells and Shell Programming As discussed in Chapter 19, a shell is a command-line interpreter program. It receives your typed-in commands when using the Terminal (or a … - Selection from Mac OS X in a Nutshell [Book]
Shell编程:简洁的 Bash Programming 技巧(三),这是简洁的BashProgramming技巧系列的第三篇文章,这一系列的文章专门介绍Bas
command1 command2 ... commandN:当条件为真时执行的一系列命令。 fi:结束if语句。 if单行写法 if [ $(ps -ef | grep -c "bash") -gt 1 ]; then echo "true"; fi $(...):命令替换,执行括号内的命令,并将输出替换到当前位置。 [...]:条件测试,用于判断括号内的表达式是否为真。 if-else语句...
After adding them, run the command below to activate. source ~/.bashrc 3. Linux Shell Reserved Words In shell programming, words such asif,then,fi,for,while,case,esac,else,until,and many others are shell-reserved words. As the description implies, they have specialized meaning to the shell...
1. 内置命令null command:nop,表示什么都不做,也可以被当作true值使用; $ : $ echo $? # return 0 1. 2. 它也可以在循环中当作true值,例如: while :; do # 等价于 while true; do take-some-action done if condition then : else take-some-action ...
原作名:Linux Command Line and Shell Scripting Bible, Second Edition 译者:武海峰 出版年:2012-9 页数:619 定价:99.00元 装帧:平装 丛书:图灵程序设计丛书·Linux/UNIX系列 ISBN:9787115288899 豆瓣评分 8.4 274人评价 5星 42.0% 4星 40.9% 3星 15.0% ...
In this chapter we are going to look at some of the “magic” that occurs on the commandline when you press the enter key. While we will examine several interesting andcomplex features of the shell, we will do it with just one new command: 在这一章我们将看到,当你按下 enter 键后,发...