echo"$1 exists." else echo"$1 is not exists." fi #运行脚本时,后接参数root,youshine,ehhe就是通过$1传递给脚本的 练习中的/dev/null,是黑洞,当我们不需要命令返回信息时,即可指向它。 if语句中通过命令执行的状态返回值(可以在当前命令执行后,echo $?查看)进行判断, 0表示成功执行,1-255表示执行失...
if [ $Shell == /bin/bash ]; then #如有需要此处的字符或变量用双引号,如字符间有空格时 echo "$1's shell is bash." Ret=5 else echo "$1's shell is not bash." Ret=7 fi else echo "$1 is not exists." Ret=9 fi done exit $Ret #echo $? 状态返回值即可判断执行的是脚本中哪一...
$ if ls exists.txt; then echo yes; else echo no; fi exists.txt yes $ if ls not_exists.txt; then echo yes; else echo no; fi ls: cannot access not_exists.txt: No such file or directory no 可以把if关键词的作用当成:判断后面跟着的命令的$?是否为 0。 这里ls 也输出我们不需要的信息,...
[student@studentvm1 testdir]$ File="TestFile1" ; echo "This is $File" > $File ; if [ -s $File ] ; then echo "$File exists and contains data." ; elif [ -e $File ] ; then echo "$File exists and is empty." ; else echo "$File does not exist." ; fi TestFile1 exists ...
This is the job of the test command, which can check if a file exists and its type. Since only the check is completed, the test command sets the exit code to 0 or 1 (either false or true, respectively) whether the test is successful or not. ...
/bin/bash # Calculate the week number using the date command: WEEKOFFSET=$[ $(date +"%V") % 2 ] # Test if we have a remainder. If not, this is an even week so send a message. # Else, do nothing. if [ $WEEKOFFSET -eq "0" ]; then echo "Sunday evening, put out the ...
$ bash simpleif.sh4Start program You entered4End program 如果要处理额外的情况,我们需要加一个ELSE语句块: 代码语言:javascript 复制 #!/usr/bin/env bash# File:simpleifelse.sh echo"Start program"if[[$1-eq4]]then echo"Thanks for entering $1"elseecho"You entered: $1, not what I was lookin...
#!/bin/bash # if [ $# -ge 1 ]; then if ! id $1 &>/dev/null;then useradd $1 fi fi 1. 2. 3. 4. 5. 6. 7. 方法二: #!/bin/bash if !id $1 & >> null;then useradd $1 else echo "the user exists" fiif可以嵌套: if CONDITION1; then if CONDITION2; then CMD fi fi...
This is most likely not the correct error caused byhttps://github.com/docker/docker/blob/master/daemon/start.go#L142 Where it's not checking if the returned error is mentioning the container command or some other path as not found.
anny ~> ./msgcheck.sh This scripts checks the existence of the messages file. Checking... /var/log/messages exists. ...done. 7.1.1.4. 检查shell选项 加入到你的Bash配置文件中去: # These lines will print a message if the noclobber option is set: ...