[英]syntax error near unexpected token `(' with "let" command in bash script
我有一個 bash 腳本如下,它會生成伴隨的錯誤:
# cat ./a.sh
#!/bin/bash
let C=1+(2)
echo $C
#
# ./a.sh
./a.sh: line 2: syntax error near unexpected token `('
./a.sh: line 2: `let C=1+(2)'
但是,它可以從命令行按預期工作:
# let C=1+(2)
# echo $C
3
如果我將腳本中的“let”表達式更改為以下內容,它也可以工作:
C=$((1+(2)))
我的bash版本如下:
# /bin/bash --version
GNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
操作系統是 CentOS 7.7
啊,這是罪魁禍首:在交互式 session 中:
$ declare -p BASH_VERSINFO
declare -ar BASH_VERSINFO='([0]="4" [1]="2" [2]="45" [3]="1" [4]="release" [5]="i386-apple-darwin19.5.0")'
$ let C=1+(2) && echo $C
3
$ shopt -u extglob
$ let C=1+(2) && echo $C
bash: syntax error near unexpected token `('
+(pattern)
是一個擴展的 glob 模式,當關閉extglob
時,它顯然是非法的語法。
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