Can Perl one-liner print matching pattern lines to a file and delete that lines in the original file-CodePudding

I have a file1 which has lines

abc
dfg
hij
cab

I would like to match the pattern ab in file1 and print to file2. After that delete those lines from file1. Then file1 has the following lines

dfg
hij

and file2 has lines

abc
cab

Currently, I am doing it with two lines of code

perl -ne '/ab/i && print' file1.csv > file2.csv
perl -n -i.bak -e 'print unless m/ab/' file1.csv

Can any one give me a one-liner Perl code?

Thanks,

CodePudding user response：

I'd use ed instead:

$ rm file2.csv # Just in case it already exists
$ ed -s file1.csv <<'EOF'
g/ab/.W file2.csv\
d
w
EOF

(For every line matching the basic regular expression ab, append it to file2.csv and delete the line, and then finally write the modified buffer back to file1.csv).

But one simple perl one-liner:

$ perl -ni -e 'if (/ab/) { print STDERR } else { print }' file1.csv 2>file2.csv

This prints matching lines to standard error and uses the shell to redirect that to file2.csv, while modifying file1.csv in-place with just the non-matching lines.