你如何检查一个文本文件是否有制表符作为它在 bash 中的分隔符？
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How do you check if a text file had tab as its delimiter in bash?
提问by Redson
So I have a text file and it may have a tab as its field separator (delimiter) or it may have a space as a field separator. I would like to check if that text file is tabulated otherwise I will do something else with the file. I am using a bash script. So i'm open to anything with pure bash, sed, awk, grep, etc. (NOTE: that they are all GNU). So I am thinking of a structure like this:
所以我有一个文本文件，它可能有一个制表符作为它的字段分隔符（分隔符），或者它可能有一个空格作为字段分隔符。我想检查该文本文件是否已制成表格，否则我将对文件执行其他操作。我正在使用 bash 脚本。所以我对任何纯 bash、sed、awk、grep 等都持开放态度（注意：它们都是 GNU）。所以我在考虑这样的结构：
if [if delimiter is tab]; then
#do soemthing
elif [if delimiter is space]; then
#do something else
fi
Any suggestions? Let me know if further explanation is required. Thanks!
有什么建议？如果需要进一步解释，请告诉我。谢谢！
Here is an explanation updateon what the text file looks like:
以下是有关文本文件外观的说明更新：
If the text file has a tab as delimiter, then it delimited on every line. If the text file has a space as delimiter, then it is NOT delimited every line.
如果文本文件有一个制表符作为分隔符，那么它会在每一行上分隔。如果文本文件有一个空格作为分隔符，那么它不会每行分隔。
Here are examples of possible text files that I might be facing:
以下是我可能面临的可能文本文件的示例：
Delimiter is tab:
分隔符是制表符：
col1 col2 col3
-------
1 2 3
4 5 6
Delimiter is space: (the space is between 12 and 3 && 4 and 56)
分隔符是空格：（空格在 12 和 3 && 4 和 56 之间）
col1col2col3
-----------
12 3
4 56
回答by Etan Reisner
Assuming a tab will only exist on the first line when the file is tab delimited then this
假设当文件以制表符分隔时，制表符仅存在于第一行，则此
if awk '{exit !/\t/}' "$file"; then
: # tab file
else
: # space file
fi
should do what you want.
应该做你想做的。
Also:
还：
if [ -n "$(sed -n '/\t/p;q' "$file")" ]; then
: # tab file
else
: # space file
fi
回答by Dylan
The above solutions only check that there are tabs somewhere, not that the file is correctly formatted, i.e. that each line has 3 tab-separated columns.
上述解决方案只检查某处是否有制表符，而不是检查文件格式是否正确，即每行有 3 个制表符分隔的列。
I'd use something like the following, which checks that each line has the correct number of tabs:
我会使用类似以下的东西，它检查每一行是否有正确数量的选项卡：
no_cols=3
no_lines=$(cat "${file}" | wc -l)
no_tab_lines=$(cat "${file}" | cut -f${no_cols} | sed '/^$/d' | wc -l)
if [[ ${no_lines} -eq ${no_tab_lines} ]]; then
echo "tabs"
else
echo "not all tabs"
fi
回答by jaybee
If it is enough to test whether we have a tab on the first line, I would go without calling awk:
如果足以测试我们是否在第一行有一个选项卡，我将不调用awk：
if `head -1 $file | grep -q ' '`; then
: # tab file
else
: # space file
fi
where the "spaces" between the two single quotes are made with Ctrl-V followed by hitting the tab key.
其中两个单引号之间的“空格”是用 Ctrl-V 然后按 Tab 键。
