如果您想处理除最简单 CSV 文件之外的任何内容，您可能应该将sed 和awk 移出。有更好的工具可用。
例如，如果您在自己喜欢的发行版上使用sudo apt install csvtool（或同等版本），则可以使用其每行调用功能来处理输入文件中的每一行。有关示例，请参见以下脚本：
#!/bin/bash
function quotify {
# Start empty line, process every field.
line=""
while [[ $# -ne 0 ]] ; do
# Append comma for all but first field, then quoted field.
[[ -n "${line}" ]] && line="${line},"
line="${line}\"$1\""
shift
done
# Output the fully quoted line.
echo "${line}"
}
# Needed to call functions. Also, ensure link: /bin/sh -> /bin/bash.
export -f quotify
# Pretty-print input and output.
echo "Input file:"
sed 's/^/ /' inputFile.csv
echo "Output file:"
csvtool call quotify inputFile.csv | sed 's/^/ /'
注意 quotify 函数，该函数为 CSV 文件中的每个 line 调用，参数设置为该行中的每个 field（无引号，是否原始字段是否有引号）。
它基本上构造了一行中所有字段的字符串，并在它们周围加上引号，然后将其写入标准输出，如下面该脚本的输出所示：
Input file:
378478,COMPLETED,Tracfone,,,"2020/03/29 09:39:22",,2787,,356074101197544,89148000005748235454,75176540
378328,COMPLETED,"Total Wireless","Unlimited Talk, Text, & Data (First 25GB High Speed, then unlimited 2GB)",50,"2020/03/29"
Output file:
"378478","COMPLETED","Tracfone","","","2020/03/29 09:39:22","","2787","","356074101197544","89148000005748235454","75176540"
"378328","COMPLETED","Total Wireless","Unlimited Talk, Text, & Data (First 25GB High Speed, then unlimited 2GB)","50","2020/03/29"
即使使用单独的工具可能是最简单的方法，但如果您绝对无法安装其他软件包，那么您将不得不在已有的软件包中编写一些代码。以下bash 脚本是一个很好的起点，因为它不使用其他工具来实现其目标。
目前，它与一组非常具体的规则相关联，如下所示：
- 空白很重要。逗号之间的任何内容都被视为该字段的一部分。这在检测带引号的字段时尤其重要，它必须将引号作为第一个字符，没有
abc, "d,e,f",ghi 的东西，因为 "d,e,f" 将无法正确处理。
- 引用字段允许包含逗号，其中的
""序列转换为"。
- 提供格式错误的 CSV 文件可能不是一个好主意 :-)
但是，考虑到这一点，我们开始吧。我将提供每个部分的简短文字说明，但希望代码中的 cmets 足以弄清楚发生了什么。
首先，一个用于查找某个字符串在另一个字符串中的位置的函数，用于计算字段边界：
function findPos {
haystack="$1"
needle="$2"
# Remove everything past the needle.
prefix="${haystack%%${needle}*}"
# If nothing was removed, it wasn't found, so supply massive number.
# Otherwise, it was found at the length of the string with removed stuff.
position=999999
[[ ${#prefix} -ne ${#haystack} ]] && position=${#prefix}
echo ${position}
}
然后我们可以在计算下一个字段长度的函数中使用它。这基本上只是为未引用的字段查找下一个逗号，并通过从段中构建字段来对引用的字段进行特殊处理（它必须处理引号和逗号中的引号）：
function getNextFieldLen {
line="$1"
# Empty line means all work done.
[[ -z "${line}" ]] && echo -1 && return
# Handle unquoted first, this is easy.
[[ "${line:0:1}" != '"' ]] && { echo $(findPos "${line}" ","); return; }
# Now handle quoted. Loop over all segments where a segment is defined as
# the text up to the next <"">, assuming it's before the next <",>.
field=""
nextQuoteComma=$(findPos "${line}" '",')
nextDoubleQuote=$(findPos "${line}" '""')
while [[ ${nextDoubleQuote} -lt ${nextQuoteComma} ]]; do
# Append segment to the field and go back for next segment.
field="${field}${line:0:${nextDoubleQuote}}\"\""
line="${line:${nextDoubleQuote}}"
line="${line:2}"
nextQuoteComma=$(findPos "${line}" '",')
nextDoubleQuote=$(findPos "${line}" '""')
done
# Add final segment (up to the comma) and output entire field.
field="${field}${line:0:${nextQuoteComma}}\""
echo "${#field}"
}
最后，有一个顶级函数将引用通过标准输入输入的任何内容：
function quotifyStdIn {
# Process file line by line.
while read -r line; do
# Start with empty output line and non-comma separator.
outLine="" ; sep=""
# Place terminator to make processing easier, start field loop.
line="${line},"
fieldLen=$(getNextFieldLen "${line}")
while [[ ${fieldLen} -ge 0 ]]; do
# Get field and quotify if needed, adjust line (remove field and comma).
field="${line:0:${fieldLen}}"
[[ "${field:0:1}" = '"' ]] || field="\"${field}\""
line="${line:$((fieldLen+1))}"
#line="${line:${fieldLen}}"
#line="${line:1}"
# Append to output line and prepare for next field.
outLine="${outLine}${sep}${field}"; sep=","
fieldLen=$(getNextFieldLen "${line}")
done
# Output built line.
echo "${outLine}"
done
}
而且，如果您想直接从文件中读取数据（尽管提供空文件名或 "-" 将使用标准输入，因此您可能只使用基于文件的函数来处理所有内容）：
function quotifyFile {
file="$1"
# Empty file or "-" means standard input, otherwise take input from real file.
[[ ${#file} -eq 0 ]] && { quotifyStdIn; return; }
[[ "${file}" = "-" ]] && { quotifyStdIn; return; }
quotifyStdIn < "${file}"
}
最后，因为每个程序不是“Hello, world”的程序都值得某种形式的测试工具，这就是您可以用来测试各种功能的工具：
(
echo 'paxdiablo,was here'
echo 'and,"then, strangely,",he,was,not'
echo '50,"My name is ""Pax"", and yours is ""Bob""",42'
echo '17,"""Love"" is grand",19'
) > harness.csv
echo "Before:"
sed "s/^/ /" harness.csv
echo "After:"
quotifyFile harness.csv | sed "s/^/ /"
rm -rf harness.csv
而且，由于除非您运行测试，否则测试工具几乎没有用处，以下是第一次运行的结果：
Before:
paxdiablo,was here
and,"then, strangely,",he,was,not
50,"My name is ""Pax"", and yours is ""Bob""",42
17,"""Love"" is grand",19
After:
"paxdiablo","was here"
"and","then, strangely,","he","was","not"
"50","My name is ""Pax"", and yours is ""Bob""","42"
"17","""Love"" is grand","19"
希望这足以让您在无法安装软件包的情况下继续前进。当然，如果您无法在 bash 本身中安装其中一个软件包，那么您遇到的问题我无法帮助您解决:-)