= str2 当字符串 str1 和 str2 不等时为真 -n str1 当字符串的长度大于 0 时为真(串非空) -z str1 当字符串的长度为 0 时为真(空串) str1 当字符串 str1 为非空时为真 数值的判断 int1 -eq int2 两数相等为真 int1 -ne int2 两数不等为真 int1 -gt
bash 中的条件语句，基础就是 Test 。 if 先来个实例： x=5; if [ $x = 5 ]; then e...
shell bash：在if语句中使用条件AND OR你不需要for循环，也不需要[[...]]条件结构，你只需要模式匹配...
[ian@pinguino ~]$ function mycalc () > { > local x > if [ $# -lt 1 ]; then > echo "This function evaluates arithmetic for you if you give it some" > elif (( $* )); then > let x="$*" > echo "$* = $x" > else > echo "$* = 0 or is not an arithmetic expression"...
if语句 使用命令的退出状态 比较和测试输入和文件 if/then/else结构 if/then/elif/else结构 使用和测试位置参数 嵌套if语句 布尔表达式 使用case语句 7.1. 介绍if 7.1.1. 概要 有时候你需要指定shell脚本中的依靠命令的成功与否来实施不同过程的行为。if结构允许你来指定这样的条件。
if [[ $foo =~ $re ]] 36. [ -n $foo ] or [ -z $foo ] 这个例子中, 没有用引号引起来,当foo 包含空格或者 $foo 为空时都会出问题: $ foo="some word" && [ -n $foo ] && echo yes -bash: [: some: binary operator expected ...
find_lock.sh - tries to find if a lockfile is used in the given or current working directory by taking snapshots of the file list before and after a prompt in which you should open/close an application foreach_path_bin.sh - runs each binary of the given name found in $PATH with the...
~/.nvm/nvm.sh. Restarting your terminal/opening a new tab/window, or running the source command will load the command and the new configuration. If the above didn't help, you might need to restart your terminal instance. Try opening a new tab/window in your terminal and retry....
if语句用来检验一个条件, 如果 条件为真,我们运行一块语句(称为 if-块 ), 否则 我们处理另外一块语句(称为 else-块 )。 else while语句 只要在一个条件为真的情况下,while语句允许你重复执行一块语句。while语句是所谓 循环 语句的一个例子。while语句有一个可选的else从句。
If you surround a string of characters with single quotation marks (or quotes), you strip all characters within the quotes of any special meaning they might have. The most obvious situation where you might need to quote a string is with the echo command, which just takes its arguments and ...