问题
Assuming I have a file BookDB.txt which stores data in the following format :
Harry Potter - The Half Blood Prince:J.K Rowling:40.30:10:50
The little Red Riding Hood:Dan Lin:40.80:20:10
Harry Potter - The Phoniex:J.K Rowling:50.00:30:20
Harry Potter - The Deathly Hollow:Dan Lin:55.00:33:790
Little Prince:The Prince:15.00:188:9
Lord of The Ring:Johnny Dept:56.80:100:38
Three Little Pig:Andrew Lim:89.10:290:189
All About Linux:Ubuntu Team:76.00:44:144
Catch Me If You Can:Mary Ann:23.60:6:2
Python for dummies:Jared Loo:15.99:1:10
I am trying to replace the (:) delimiter with (, ) in my output. It succeeds, but removes the newline from the output. Here is my code :
TITLE=Potter
OUTPUT=$(cat BookDB.txt | grep $TITLE)
OUTPUT1=$(sed 's/:/, /g' <<< $OUTPUT)
echo $OUTPUT1
I want my output to look like this :
Harry Potter - The Half Blood Prince, J.K Rowling, 40.30, 10, 50
Harry Potter - The Phoniex, J.K Rowling. 50.00. 30. 20
Harry Potter - The Deathly Hollow, Dan Lin, 55.00, 33, 790
However, it looks like this :
Harry Potter - The Half Blood Prince, J.K Rowling, 40.30, 10, 50 Harry Potter - The Phoniex, J.K Rowling, 50.00, 30, 20 Harry Potter - The Deathly Holl
ow, Dan Lin, 55.00, 33, 790
If anyone could share how to preserve the line break in the output, I would be very grateful!
回答1:
Just use correct quotation :
TITLE=Potter
OUTPUT=$(cat BookDB.txt | grep $TITLE)
OUTPUT1=$(sed 's/:/, /g' <<< "$OUTPUT")
echo "$OUTPUT1"
As \n is part of the default value of IFS, it is removed without the double quotes.
More info on quoting here
回答2:
You can avoid cat and do all in sed:
sed -n '/Potter/s/:/, /gp' file
Harry Potter - The Half Blood Prince, J.K Rowling, 40.30, 10, 50
Harry Potter - The Phoniex, J.K Rowling, 50.00, 30, 20
Harry Potter - The Deathly Hollow, Dan Lin, 55.00, 33, 790
回答3:
Using awk. Matching would be specific to the titles and doesn't include the author's name.
awk -F: -v OFS=', ' '$1 ~ /Potter/ { $1 = $1; print }' file
Output:
Harry Potter - The Half Blood Prince, J.K Rowling, 40.30, 10, 50
Harry Potter - The Phoniex, J.K Rowling, 50.00, 30, 20
Harry Potter - The Deathly Hollow, Dan Lin, 55.00, 33, 790
This gives no output:
awk -F: -v OFS=', ' '$1 ~ /Rowling/ { $1 = $1; print }' file
But this will:
awk -F: -v OFS=', ' '$2 ~ /Rowling/ { $1 = $1; print }' file
Output:
Harry Potter - The Half Blood Prince, J.K Rowling, 40.30, 10, 50
Harry Potter - The Phoniex, J.K Rowling, 50.00, 30, 20
To match against both title and author you can have:
awk -F: -v OFS=', ' '$1 ~ /Potter/ && $2 ~ /Rowling/ { $1 = $1; print }' file
Or to match if any validates:
awk -F: -v OFS=', ' '$1 ~ /Potter/, $2 ~ /Rowling/ { $1 = $1; print }' file
来源：https://stackoverflow.com/questions/25114517/bash-how-to-preserve-newline-in-sed-command-output