问题
How to remove the special characters shown as blue color in the picture 1 like: ^M, ^A, ^@, ^[. In my understanding, ^M is a windows newline character, I can use sed -i '/^M//g' to remove it, but it doesn't work to remove others. The command dos2unix doesn't work, neither. Are there exist any ways that I can use to remove them both?
回答1:
Remove everything except the printable characters (character class [:print:]), with sed:
sed $'s/[^[:print:]\t]//g' file.txt
[:print:] includes:
[:alnum:](alpha-numerics)[:punct:](punctuations)- space
The ANSI C quoting ($'') is used for interpreting \t as literal tab inside $'' (in bash and alike).
回答2:
To ensure that the command works with limited scope in Sed, force use of the "C" (POSIX) character classifications to avoid unpredictable behavior with non-ASCII characters:
LC_ALL=C sed 's/[^[:blank:][:print:]]//g' file.txt
回答3:
Try running below command on linux command prompt
Option - 1: (If dos2unix command is installed on Linux machine)
dos2unix sample_file.txt
Option - 2:
cat sample_file.txt | tr -d '\015' > new_sample_file.txt
回答4:
Try this inside vi or vim:
[in ESC mode] type: :%s/^M//g
or:
sed -e "s/^M//" filename > newfilename
Important: To enter ^M, type CTRL-V, then CTRL-M
来源：https://stackoverflow.com/questions/43108359/how-to-remove-all-special-characters-in-linux-text