if(access(file_name, F_OK ) != -1) {//file exists}else{//file doesn't exist} You can also useR_OK,W_OK, andX_OKin place ofF_OKto check for read permission, write permission, and execute permission (respectively) rather than existence, and you can OR any of them together (i.e...
if[-z`git config user.name`]&&[-z`git config user.email`];then local git_remote=`git remote -v`if[[$git_remote=~"github"]];then`git config user.name "github" && git config user.email "github@youclk.com"`elif[[$git_remote=~"gitee"]];then`git config user.name "gitee" && gi...
Putting it all together, you get something like “ls tried to open /dsafsda but couldn’t because it doesn’t exist.” This may seem obvious, but these messages can get a little confusing when you run a shell script that includes an erroneous command under a different name. 综合起来,你...
写法2:我们创建一个用户,将该用户在/etc/passwd里面的信息删除,当看到这里的时候我们似乎看出了点特点,这就是嵌套if语句的特点:之前学到如果if语句行的命令的退出状态为非0,所有的命令都会被跳过,但是会输出else和elif后面的语句,这就相当于是否则判断语句;但if语句行如果为0时,则后面的语句也不会再执行(如第一...
Example 1: Check the Existence of the File Using the -F Operator with Single Third Brackets ([]) Create a Bash file with the following script that takes the filename from the user and check whether the file exists in the current location or not using the -f operator in the “if” con...
--file=ARCHIVE 使用归档文件或 ARCHIVE 设备 --force-local 即使归档文件存在副本还是把它认为是本地归档 -F, --info-script=名称, --new-volume-script=名称 在每卷磁带最后运行脚本(隐含 -M) -L, --tape-length=NUMBER 写入 NUMBER × 1024 字节后更换磁带 -M, --multi-volume 创建/列出/解压多卷归...
if command then command else command if 当if语句中的命令返回退出状态码0时,then部分中的命令会被执行,这跟普通的if-then语句一样。当if语句中的命令返回非零退出状态码时,bash shell会执行else部分中的命令。 #!/bin/bash # testing the else section ...
In Bash you can use the test command to check whether a file exist and determine the type of the file.
[root@web-server01~/script]#vimlogin.sh #!/bin/bash #CheckFiletochange. #Byauthorrivers2021-9-27 USERS="hbs" whiletrue do echo"TheTimeis`date+%F-%T`" sleep10 NUM=`who|grep"$USERS"|wc-l` if[[$NUM-ge1]];then echo"The$USERSislogininsystem." ...
# check file if exists , if not exit script. function checkFile() { if [ ! -f "$1" ]; then echo "$1 is not exitst" exit 1 fi } # install complie tools yum -y install gcc gcc-c++ make wget tar # temp dir mkdir -p /tmp/make_nginx ...