获取文件名/文件扩展名
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| ~% FILE="example.tar.gz"
~% echo "${FILE%%.*}"
example
~% echo "${FILE%.*}"
example.tar
~% echo "${FILE#*.}"
tar.gz
~% echo "${FILE##*.}"
gz
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https://stackoverflow.com/questions/965053/extract-filename-and-extension-in-bash
去除字符串的前缀/后缀
有一个字符串为hello-world, 现在希望去除前缀hell和后缀ld, 得到新的字符串o-wor
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| string="hello-world"
prefix="hell"
suffix="ld"
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方法如下:
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| $ foo=${string#"$prefix"}
$ foo=${foo%"$suffix"}
$ echo "${foo}"
o-wor
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https://stackoverflow.com/questions/16623835/remove-a-fixed-prefix-suffix-from-a-string-in-bash
手动向stderr输出
https://stackoverflow.com/questions/2990414/echo-that-outputs-to-stderr
创建临时文件夹
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| # 创建临时文件夹
$ mktemp -d
/tmp/tmp.vwjuFmclTR
# 创建临时文件夹，并指定模板
$ mktemp -d -t test-XXXXX
/tmp/test-4kceq
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https://code-maven.com/create-temporary-directory-on-linux-using-bash
判断字符串是否为空
正确做法
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| #!/bin/sh
STRING=
if [ -z "$STRING" ]; then
echo "STRING is empty"
fi
if [ -n "$STRING" ]; then
echo "STRING is not empty"
fi
---------------
输出正确结果：
root@james-desktop:~# ./zerostring.sh
STRING is empty
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错误做法
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| #!/bin/sh
STRING=
if [ -z $STRING ]; then
echo "STRING is empty"
fi
if [ -n $STRING ]; then
echo "STRING is not empty"
fi
---------------------
输出错误结果：
root@james-desktop:~# ./zerostring.sh
STRING is empty
STRING is not empty
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https://www.cnblogs.com/cute/archive/2011/08/26/2154137.html
更多用法： https://www.cyberciti.biz/faq/unix-linux-bash-script-check-if-variable-is-empty/