1. sed will read data from the file line by line, to the screen again after data processing, and then processing the next line.
sed '4d' file.txt # delete files in line 4
sed '2,6d' file.txt # delete a file in rows 2-6
2. sed in regular use:
sed with the grep command, by default it does not support extended metacharacters solution:
1. The expansion element becomes substantially slash characters plus the corresponding character element.
2. sed -r -r parameter is added, supports extended meta-characters.
3. sed use the Find and Replace:
Alternative uses:
1. sed -r 's / xx / XX /' # is replaced xx XX, the replacement of only one of each row
2. sed -r 's / xx / XX / g' # replace a line of all xx XX
3. sed -r 's / xx / XX / gi' # ignores row matches the case of replacement content
Find the use of:
1. sed -r '/ xx / d' # Do not use Find s, find and delete xx