echo "a + b : $val" val=`expr $a - $b` echo "a - b : $val" val=`expr $a \* $b` echo "a * b : $val" val=`expr $b / $a` echo "b / a : $val" val=`expr $b % $a` echo "b % a : $val" if [ $a == $b ] then echo "a == b" fi if [ $a !=...
写bash 脚本的日子也不短了,但是每次用到 if 语句时大脑还是会卡壳一下,要翻教程和看以前的代码,因为条件部分语法神出鬼没,捉摸不定,于是我还是花点时间狠狠研究了一下,写了这篇文章做总结。诡异的语法一般bash 教程给出的语法示例基本就是:if condition; then echo yes else echo no fi 看起来很简单,除了...
/bin/bash myPath="/var/log/nginx/"myFile="/var /log/nginx/access.log"# -x 参数 判断$myPath是否存在并且是否具有可执行权限if [ ! -x"$myPath"];thenmkdir"$myPath"fi# -d 参数 判断$myPath是否存在,并且属性是个目录if [ ! -d"$myPath"];thenmkdir"$myPath"fi# -f参数 判断$myFile是...
# Check if a file exists if [ -f $file ] then echo "File exists" else echo "File does not exist" fi # Check if a command is successful if ls then echo "Command succeeded" else echo "Command failed" fi ``` 通过使用if-else语句,用户可以根据不同的条件执行不同的操作。这使得Bash脚本...
#!/bin/bash if [ -z $1 ];then echo "you entered nothing" exit 1 else if [ -e $1 ]; then echo "the file exists" else echo "the file doesn't exist" fi fi 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 练习13:写一个脚本,传递一个文件路径参数给脚本 (1) 如果脚本无参数,则...
File/usr/bin/boot.ini exists 请参阅之前的文章以了解各种bash if 语句类型。 Bash 示例 2. 比较数字 下面的脚本从用户那里读取两个整数,并检查这两个数字是否相等或大于或小于彼此。 $ cat numbers.sh #!/bin/bash echo"Please enter first number"read first ...
The result of bash's regex matching can be used to replace sed for a large number of use-cases.CAVEAT: This is one of the few platform dependent bash features. bash will use whatever regex engine is installed on the user's system. Stick to POSIX regex features if aiming for ...
#Input file _db="/tmp/wordpress/faq.txt" #Output location o="/var/www/prviate/pdf/faq" _writer="~/bin/py/pdfwriter.py" # If file exists if [[ -f "$_db" ]] then # read it while IFS='|' read -r pdfid pdfurl pdftitle ...
/usr/bin/env bash# File:simpleif.sh echo"Start program"if[[$1-eq4]]then echo"You entered $1"fi echo"End program" 我们来看看运行结果,首先不带参数: 代码语言:javascript 代码运行次数:0 复制 Cloud Studio代码运行 $ bash simpleif.sh
Here, we list some basic bash syntax with a brief explanation. It is a good starting point if you are a beginner.