代码语言:javascript 代码运行次数:0 运行 AI代码解释 #!/bin/bashSTR="Hello World"echo $STR 当我运行 bash test.sh 时,我会得到以下信息: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 test.sh:line2:STR:command not found 我做错了什么?我在网上看过一些非常基础/初学者的 bash 脚本教程,这是...
9. if [grep foo myfile] 初学者会错误地认为,[是 if 语法的一部分,正如 C 语言中的 if ()。但是事实并非如此,if 后面跟着的是一个命令,[是一个命令,它是内置命令 test 的简写形式,只不过它要求最后一个参数必须是]。下面两种写法是一样的: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 #POSIX...
declare -rx wc=”/usr/bin/wc” # wc command # Sanity checks if test -z “$BASH” ; then printf “Please run this script with the BASH shell/n” >&2 exit 192 fi if test ! -x “$ls” ; then printf “$SCRIPT:$LINENO: the command $ls is not available — aborting/n “ >&2...
If no COMMAND is specified the WGET_ASKPASS or the SSH_ASKPASS environment variable is used. --no-iri turn off IRI support --local-encoding=ENC use ENC as the local encoding for IRIs --remote-encoding=ENC use ENC as the default remote encoding --unlink remove file before clobber --keep...
How to check if a command succeeds or failed? How to do string comparison and check if a string equals to a value? How to check if a string is in an array? How to use the Bash ternary operator? How to negate an if condition in a Bash if statement? (if not command or if not ...
test EXPRESSION [ EXPRESSION ] ` EXPRESSION ` COMMAND 测试表达式: 整数测试:A, B A -gt B: 大于 A -ge B: 大于等于 A -eq B: 等于 A -lt B: 小于 A -le B: 小于等于 A -ne B: 不等于 当判断与整数相关的条件时 如上图:通过判断用户ID大小,来确定用户是管理员还是普通用户还是系统用户。
if [ "$?" -ne 0 ]; then echo "cmd failed";exit 1;fi # 写法四 命令1 && 命令2 上面那种常规方法,写法比较麻烦,所以set -e 参数解决了这一烦恼 #!/usr/bash set -e var echo "hello world" 执行上面脚本,结果如下 test: line 5: var: command not found ...
The bash test command is used to check the validity of an expression. It checks whether a command or an expression is true or false. Also, it can be used to check the type and permissions of a file. If the command or expression is valid, thetestcommand returns a0else it returns1. ...
While ShellCheck is mostly intended for interactive use, it can easily be added to builds or test suites. It makes canonical use of exit codes, so you can just add ashellcheckcommand as part of the process. For example, in a Makefile: ...
trap 'echo "$BASH_COMMAND" failed with error code $?' ERR #!/usr/bin/env bash # Filename: ./example-xtrace echo "This got executed" v=$1 if [[ -z "${v}" ]]; then echo "\$v is empty" fi ## Output [me@linux ~]$ TRACE=1 BASH_ENV=my-debug-env ./example-xtrace ...