如何在BASH中将制表符分隔值(TSV)文件转换为逗号分隔值(CSV)文件?(How do I convert a tab-separated values (TSV) file to a comma-separated values (CSV) file in BASH?)

我有一些TSV文件需要转换为CSV文件. BASH中是否有任何解决方案，例如使用awk来转换这些?我可以这样使用sed，但担心它会出错:

sed 's/\t/,/g' file.tsv > file.csv

• 不需要添加行情.

如何将TSV转换为CSV?

解决方案

更新:尽管以下解决方案总体上不可靠 在OP的特定用例中进行工作；请参见底部部分，以获取基于awk的可靠解决方案.

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总结选项(有趣的是，它们的表现大致相同):

tr :

devnull的解决方案(在问题注释中提供)是最简单的:

tr '\t' ',' < file.tsv > file.csv

固定:

OP自己的sed解决方案非常好，因为输入不包含带引号的字符串(可能嵌入了\t字符.):

sed 's/\t/,/g' file.tsv > file.csv

唯一需要注意的是，在某些平台(例如macOS)上，不支持转义序列\t，因此使用文字制表符char.必须使用ANSI引号($'\t')拼接到命令字符串中:

sed 's/'$'\t''/,/g' file.tsv > file.csv

awk :

awk的警告是FS-输入字段分隔符-必须设置为\t 明确-默认行为否则会剥离前导和尾随制表符并替换内部跨度只有一个,

的多个选项卡

awk 'BEGIN { FS="\t"; OFS="," } {$1=$1; print}' file.tsv > file.csv

请注意，简单地为其分配$1会导致awk使用OFS- output 字段分隔符重建输入行；这有效地替换了所有\t字符.与,字符. print然后简单地打印重建的行.

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强大的awk解决方案:

为A. Rabus指出，以上解决方案无法正确处理本身包含,字符的未加引号的输入字段-您最终将获得额外的CSV字段.

下面的awk解决方案通过按需将这些字段包含在"..."中来解决此问题(有关该方法的部分说明，请参见上面的非稳健的awk解决方案).

如果此类字段也嵌入了"字符，则会按照RFC 4180.谢谢，怀亚特以色列.

awk 'BEGIN { FS="\t"; OFS="," } {
  rebuilt=0
  for(i=1; i<=NF; ++i) {
    if ($i ~ /,/ && $i !~ /^".*"$/) {
      gsub("\"", "\"\"", $i)
      $i = "\"" $i "\""
      rebuilt=1
    }
  }
  if (!rebuilt) { $1=$1 }
  print
}' file.tsv > file.csv

• $i ~ /[,"]/ && $i !~ /^".*"$/检测到任何包含,和/或"并且尚未用双引号引起来的字段

• gsub("\"", "\"\"", $i)转义嵌入的"字符.将它们加倍

• $i = "\"" $i "\""通过将结果括在双引号中来更新结果

• 如前所述，更新任何字段都会导致awk用OFS值(即,)从字段重建在这种情况下，相当于有效的TSV-> CSV转换；标志rebuilt用于确保至少一次重新构建每个输入记录.

• 原文

I have some TSV files that I need to convert to CSV files. Is there any solution in BASH, e.g. using awk, to convert these? I could use sed, like this, but am worried it will make some mistakes:

sed 's/\t/,/g' file.tsv > file.csv

• Quotes needn't be added.

How can I convert a TSV to a CSV?

解决方案

Update: The following solutions are not generally robust, although they do work in the OP's specific use case; see the bottom section for a robust, awk-based solution.

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To summarize the options (interestingly, they all perform about the same):

tr:

devnull's solution (provided in a comment on the question) is the simplest:

tr '\t' ',' < file.tsv > file.csv

sed:

The OP's own sed solution is perfectly fine, given that the input contains no quoted strings (with potentially embedded \t chars.):

sed 's/\t/,/g' file.tsv > file.csv

The only caveat is that on some platforms (e.g., macOS) the escape sequence \t is not supported, so a literal tab char. must be spliced into the command string using ANSI quoting ($'\t'):

sed 's/'$'\t''/,/g' file.tsv > file.csv

awk:

The caveat with awk is that FS - the input field separator - must be set to \t explicitly - the default behavior would otherwise strip leading and trailing tabs and replace interior spans of multiple tabs with only a single ,:

awk 'BEGIN { FS="\t"; OFS="," } {$1=$1; print}' file.tsv > file.csv

Note that simply assigning $1 to itself causes awk to rebuild the input line using OFS - the output field separator; this effectively replaces all \t chars. with , chars. print then simply prints the rebuilt line.

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Robust awk solution:

As A. Rabus points out, the above solutions do not handle unquoted input fields that themselves contain , characters correctly - you'll end up with extra CSV fields.

The following awk solution fixes this, by enclosing such fields in "..." on demand (see the non-robust awk solution above for a partial explanation of the approach).

If such fields also have embedded " chars., these are escaped as "", in line with RFC 4180.Thanks, Wyatt Israel.

awk 'BEGIN { FS="\t"; OFS="," } {
  rebuilt=0
  for(i=1; i<=NF; ++i) {
    if ($i ~ /,/ && $i !~ /^".*"$/) {
      gsub("\"", "\"\"", $i)
      $i = "\"" $i "\""
      rebuilt=1
    }
  }
  if (!rebuilt) { $1=$1 }
  print
}' file.tsv > file.csv

• $i ~ /[,"]/ && $i !~ /^".*"$/ detects any field that contains , and/or " and isn't already enclosed in double quotes

• gsub("\"", "\"\"", $i) escapes embedded " chars. by doubling them

• $i = "\"" $i "\"" updates the result by enclosing it in double quotes

• As stated before, updating any field causes awk to rebuild the line from the fields with the OFS value, i.e., , in this case, which amounts to the effective TSV -> CSV conversion; flag rebuilt is used to ensure that each input record is rebuilt at least once.