在Bash Shell中,可以使用复合条件来在一个if语句中检查多个条件。复合条件主要有两种形式:逻辑与(&&)和逻辑或(||)。 逻辑与(&&): 概念:逻辑与用于同时检查多个条件,只有当所有条件都为真时,整个条件表达式才为真。 语法:condition1 && condition2 示例: 示例: 优势:逻辑与可以简化代码,将...
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...
In programming, it is essential to check if a variable is “set” or “not set,” which means you have to check if a bash script variable has a value or not. This check helps for effective data validation. However, there’s no built-in function for checking empty variables in bash sc...
Thepatternwillmatchif itmatchesanypartofthe string. Anchor thepatternusingthe ‘^’and‘$’ regular expression operatorstoforce ittomatchthe entire string. Thearrayvariable BASH_REMATCH records which partsofthe string matched the pattern. The elementofBASH_REMATCHwithindex0containstheportionofthe string...
# set variable identifying the chroot you work in (used in the prompt below) if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then debian_chroot=$(cat /etc/debian_chroot) fi # set a fancy prompt (non-color, unless we know we "want" color) ...
具体分别表示为, 记住工作路径, 和允许使用 ! 历史扩展, 详细请参阅set命令.$_(下划线) 表示的是打印上一个输入参数行, 当这个命令在开头时, 打印输出文档的绝对路径名. 举例如下: 例如我们有一个文档, test_3.sh #!/bin/bashecho“Current absolute file path name is:$_”echo“$-“echo“Second$_”...
内置的:可以用来避免在case语句中重复的实用variable =。 $ _变量存储最后一个命令的最后一个参数。 :总会成功,所以它可以用来存储变量值。case "$OSTYPE" in "darwin"*) : "MacOS" ;; "linux"*) : "Linux" ;; *"bsd"* | "dragonfly" | "bitrig") : "BSD" ;; "cygwin" | "msys" | "win...
ShellCheck will warn when using features not supported by the shebang. For example, if you set the shebang to#!/bin/sh, ShellCheck will warn about portability issues similar tocheckbashisms: echo{1..$n}# Works in ksh, but not bash/dash/shecho{1..10}# Works in ksh and bash, but ...
# shellcheck disable=SC2086,SC2048trim_all() {# Usage: trim_all " example string "set-fset-- $*printf'%s\n'"$*"set+f } 用法示例: $trim_all" Hello, World "Hello, World$name=" John Black is my name. "$trim_all"$name"John Black is my name. ...
sh --no-use ';' nvm_find_nvmrc end # ~/.config/fish/functions/load_nvm.fish function load_nvm --on-variable="PWD" set -l default_node_version (nvm version default) set -l node_version (nvm version) set -l nvmrc_path (nvm_find_nvmrc) if test -n "$nvmrc_path" set -l nvmrc...