else echo "The variable is neither 5 nor 10." fi 区别总结 逻辑结构:if with or是在一个条件中检查多个可能性,而elif是在多个条件中逐个检查。 执行路径:if with or只要有一个条件满足就会执行相应代码块,而elif会按顺序检查每个条件,直到找到一个为真的条件。 代码清晰度:对于简单的多个条件检查,if with...
The pattern will match if it matches any part of the string. Anchor the pattern using the ‘^’ and ‘$’ regular expression operators to force it to match the entire string. The array variable BASH_REMATCH records which parts of the string matched the pattern. The element of BASH_REMATC...
Bash, short for "Bourne Again SHell," is a powerful scripting language used in Unix-based operating systems. One of the fundamental constructs in Bash programming is the if statement. The if statement allows you to control the flow of your script based on specific conditions. In this article,...
{varilable#*pattern}: 查找variable中自左而右第一次被pattern匹配到的串,将此串及向左的所有内容都删除{varilable##*pattern}: 查找variable中自左而右最后一次被pattern匹配到的串,将此串及向左的所有内容都删除 {varilable%pattern*}:查找variable中自右而左第一次被pattern匹配到的串,将此串及向右的所有...
if [ $# -eq 0 ] ; then printf “%s\n” “Type--help for help.” exit 192 fi # Process the parameters while [ $# -gt 0 ] ; do case “$1” in -h | --help) # Show help printf “%s\n” “usage:$SCRIPT [-h][--help] -c companyid” ...
if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi 参考:https://stackoverflow.com/questions/3601515/how-to-check-if-a-variable-is-set-in-bash 6、换算秒为分钟、小时 代码语言:javascript 代码运行次数:0 运行 AI代码解释 #!/bin/bash a=60100 sw...
#! /bin/bash read word if (( $word = "y" || $word = "Y" )) then echo "YES" elif (( $word = "n" || $word = "N" )) then echo "NO" fi 我得到这个错误: Solution.sh: line 5: ((: y = y || y = Y : attempted assignment to non-variable (error token is "= Y...
Use the if-else statement with the -v option to check if an environment variable is set in bash. The echo command in the if block will be executed if the will
$ type -t if keyword 上面例子中,bash是文件,if是关键词。 快捷键 Bash 提供很多快捷键,可以大大方便操作。下面是一些最常用的快捷键,完整的介绍参见《行操作》一章。 Ctrl + L:清除屏幕并将当前行移到页面顶部。 Ctrl + C:中止当前正在执行的命令。
-z STRING True if string is empty. -n STRING STRING True if string is not empty. 即,test命令使用-z STRING操作符来判断STRING字符串的长度是否为 0。 如果为 0,就是空字符串,会返回 true。 具体写法是test -z STRING,使用[命令则写为[ -z STRING ]。