bash Shell Scripting 不需要'?' 文件名末尾的字符
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Shell Scripting unwanted '?' character at the end of file name
提问by premprakash
I get an unwanted '?' at the end of my file name while doing this:
我得到一个不需要的 '?' 在执行此操作时在我的文件名末尾：
emplid=$(grep -a "Student ID" "$i".txt | sed 's/(Student ID: //g' | sed 's/)Tj//g' )
#gets emplid by doing a grep from some text file
echo "$emplid" #prints employee id correctly
cp "$i" "$emplid".pdf #getting an extra '?' character after emplid and before .pdf
i.e instead of getting the file name like 123456.pdf , I get 123456?.pdf . Why is this happening if the echo prints correctly? How can I remove trailing question mark characters ?
即，我没有得到像 123456.pdf 这样的文件名，而是得到 123456?.pdf 。如果回声打印正确，为什么会发生这种情况？如何删除尾随的问号字符？
回答by Gordon Davisson
It sounds like your script file has DOS-style line endings (\r\n) instead of unix-style (just \n) -- when a script in this format, the \r gets treated as part of the commands. In this instance, it's getting included in $emplid and therefore in the filename.
听起来您的脚本文件具有 DOS 样式的行结尾 (\r\n) 而不是 unix 样式（只是 \n）——当脚本采用这种格式时，\r 被视为命令的一部分。在这种情况下，它包含在 $emplid 中，因此包含在文件名中。
Many platforms support the dos2unixcommand to convert the file to unix-style line endings. And once it's converted, stick to text editors that support unix-style text files.
许多平台支持dos2unix将文件转换为 unix 样式行尾的命令。一旦它被转换，坚持使用支持 unix 样式文本文件的文本编辑器。
EDIT: I had assumed the problem line endings were in the shell script, but it looks like they're in the input file ("$i".txt) instead. You can use dos2unix on the input file to clean it and/or add a cleaning step to the sed command in your script. BTW, you can have a single instance of sed apply several edits with the -e option:
编辑：我假设问题行结尾在 shell 脚本中，但看起来它们在输入文件 ("$i".txt) 中。您可以在输入文件上使用 dos2unix 来清理它和/或向脚本中的 sed 命令添加清理步骤。顺便说一句，您可以使用 -e 选项让 sed 的单个实例应用多个编辑：
emplid=$(grep -a "Student ID" "$i".txt | sed '-e s/(Student ID: //g' -e 's/)Tj//g' -e $'s/\r$//' )
I'd recommend againstusing sed 's/.$//'-- if the file is in unix format, that'll cut off the last character of the filename.
我建议不要使用sed 's/.$//'-- 如果文件是 unix 格式，那将切断文件名的最后一个字符。
回答by user3255079
using the file command to detect if it is pure unix or mixed with DOS.
使用 file 命令来检测它是纯 unix 还是与 DOS 混合。
DOS file: ASCII text, with CRLF line terminators
DOS 文件：ASCII 文本，带有 CRLF 行终止符
Unix file is pure ASCII file.
Unix 文件是纯 ASCII 文件。
