Linux 技巧:Bash的测试和比较函数(探密test,[,[[,((和if-then-else) if语法[Linux(bash_shell)] http://blog.csdn.net/ycl810921/article/details/4988778 1: 定义变量时, =号的两边不可以留空格. eg: gender=femal---right gender =femal---wrong gender= femal---wrong 2 条件测试语句 [ 符号的两边...
SHELL := /bin/bash current_year = $(shell date +"%Y") current_date@ [ -s test_ 浏览1提问于2019-05-05得票数 0 回答已采纳 2回答 Bash脚本检查zip文件是否为空 、 我对linux比较缺乏经验,如果某个zip文件是空的,我必须检查bash脚本-即zip不包含任何文件。我找到了这段代码: rm $filetotransfer...
for file in test[1-8].sh#for将读取test1-test8,后缀为.sh的文件 do if [ -f $file ]#判断文件在当前目录是否存在。 then echo "$file exists." fi done CTRL+D /> . ./test9.sh test2.sh exists. test3.sh exists. test4.sh exists. test5.sh exists. test6.sh exists. test7.sh exis...
-d file exists and is a directory. -e file exists (just the same as -a). -f file exists and is a regular file. -g file exists and has its setgid(2) bit set. -G file exists and has the same group ID as this process. -k file exists and has its sticky bit set. -L file ...
首先创建一个 ubuntu_test.bash的文件: #!/bin/bashset-eexportUBUNTU_CODENAME=$(lsb_release -s -c)case$UBUNTU_CODENAME intrusty)exportROS_DISTRO=indigo;;xenial)exportROS_DISTRO=kinetic;;bionic)exportROS_DISTRO=melodic;;*)echo"Unsupported version of Ubu...
test_func [root@c7-server ~]# bash function.shThis is just for test. 1. 2. 3. 4. 5. 6. 示例:编写一个脚本,接收一个用户名参数,输出用户名、UID和默认shell。(要求以函数的形式) #!/bin/bash userinfo() { if ! id $username &> /dev/null; then ...
file="/test.sh" # 由于没有给出条件,所以返回true if [ ! ] then echo "File exists" else echo "File not exists" fi 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 流程控制 if else 语法格式: if condition1 then command1 elif condition2 ...
初学者会错误地认为,[是 if 语法的一部分,正如 C 语言中的 if ()。但是事实并非如此,if 后面跟着的是一个命令,[是一个命令,它是内置命令 test 的简写形式,只不过它要求最后一个参数必须是]。下面两种写法是一样的: # POSIX if [ false ]; then echo "HELP"; fi ...
21. Test if File Exists 22. Check Inodes and Disk Usage 23. Send Email Example 24. Update Packages 25. Show Server Information What Is Bash Scripting Used For Before we move on to the topic of bash scripting use cases, we need to elaborate on what bash and bash scripting are. ...
$ vim test22.sh 输入代码: #!/bin/bash if [ ! -w 't.txt' ]; then touch t.txt fi echo 'test text' >> t.txt cp t.{txt,back} 运行代码: $ bash test22.sh 查看运行结果: $ ls $ cat t.txt $ cat t.back 注意: 在大括号中,不允许有空白,除非这个空白被引用或转义。