bash AWK 语法错误 - 是什么原因造成的？
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AWK syntax error - what's causing it?
提问by user710818
I have simple bash script:
我有简单的 bash 脚本：
#!/bin/sh
column=${1:-1}
awk ' {colawk='$column'+2; print $colawk}'
awk '(x=4; print $x)'
But I have received error:
但我收到了错误：
awk: (x=4; print $x)
awk: ^ syntax error
awk: cmd. line:1: (x=4; print $x)
awk: cmd. line:1: ^ unexpected newline or end of string
Why? Code in the previous line works.
为什么？上一行中的代码有效。
采纳答案by paxdiablo
Your problem is with using parentheses instead of braces. Try:
您的问题是使用括号而不是大括号。尝试：
awk '{x=4; print $x}'
instead, as in the following transcript:
相反，如以下成绩单所示：
pax$ echo a b c d e | awk '(x=4; print $x)'
awk: cmd. line:1: (x=4; print $x)
awk: cmd. line:1: ^ syntax error
awk: cmd. line:2: (x=4; print $x)
awk: cmd. line:2: ^ unexpected newline or end of string
pax$ echo a b c d e | awk '{x=4; print $x}'
d
回答by kev
An AWK program is a series of pattern action pairs, written as:
一个 AWK 程序是一系列模式动作对，写成：
condition { action }
where conditionis typically an expression and actionis a series of commands.
wherecondition通常是一个表达式，action是一系列命令。
printis not expression but a statement, so it's a syntax erroras expected.
print不是表达式而是语句，因此它是预期的语法错误。
