如何使用sed删除csv文件的第一行和最后一行

Question

I can remove the first line of csv file's starting with myfile and merge them using:

sed 1d myfile*.csv > myfile_merged.csv

I'd like to also remove the last line of the csv files.

I've tried:

sed 1d -i '$d' myfile*.csv > myfile_merged.csv

But get the error:

sed: can't read $d: No such file or directory

Answer 1

Problem is this command:

sed 1d -i '$d' myfile*.csv > myfile_merged.csv

You need not have an argument after -i ( inline replacement ) in sed otherwise it is treated as a SUFFIX to create a backup for inline replacement.

What you need is this gnu sed command:

sed -i '1d;$d' myfile*.csv

This will remove 1st and last line in each of the matched file and save it in place.

Answer 2

What you're probably trying to do is:

sed -e '1d' -e '$d' myfile*.csv > merged.csv

But this won't work, because it tells sed to remove the first and last line of ALL files, rather than EACH file. In other words, you'll strip the first line of the first file, and the last line of the last file ... and that's it.

To process each file individually, you probably need to process each file .. individually. :)

for f in myfile*.csv
    sed -e '1d;$d' "$f"
done > merged.csv

Note that while this will run in bash, it's also POSIX compatible (both the shell and sed parts). And it does not care whether your input is CSV or any other format, as long as it can be parsed line by line using sed.