“Undefined variable script”的版本间差异
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无编辑摘要 |
无编辑摘要 |
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| （未显示同一用户的1个中间版本） | |||
| 第1行： | 第1行： | ||
first file (excutable): |
first file (excutable): |
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echo |
echo $hi |
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echo |
echo 'OK!' |
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echo 'OK!' |
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run it and it prints: |
run it and it prints: |
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second file (excutable): |
second file (excutable): |
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# |
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echo 'this is tete' |
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# |
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echo |
echo $hi |
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echo |
echo 'OK!' |
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echo 'OK!' |
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run it and it prints: |
run it and it prints: |
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this is tete |
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Because 1st file have no "#"/"#!/bin/sh"/"#!/bin/csh" on the first line, |
Because 1st file have no "#"/"#!/bin/sh"/"#!/bin/csh" on the first line, |
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in most of the linux distributions, the default interpreter of a script is /bin/sh |
in most of the linux distributions, the default interpreter of a script is /bin/sh |
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2013年12月18日 (三) 11:14的最新版本
first file (excutable):
echo 'this is tete' echo $hi echo 'OK!' exit
run it and it prints:
this is tete OK!
second file (excutable):
# echo 'this is tete' echo $hi echo 'OK!' exit
run it and it prints:
this is tete hi: Undefined variable.
Because 1st file have no "#"/"#!/bin/sh"/"#!/bin/csh" on the first line, in most of the linux distributions, the default interpreter of a script is /bin/sh if it is not specified, and /bin/sh DOES NOT think an undefined variable is a problem! "#" will call csh, and print the problem.