sed -i '/first/i This line to be added' In this case,how to ignore case while searching for pattern =first
6 Answers
You can use the following:
sed 's/[Ff][Ii][Rr][Ss][Tt]/last/g' file Otherwise, you have the /I and n/i flags:
sed 's/first/last/Ig' file From man sed:
I
i
The I modifier to regular-expression matching is a GNU extension which makes sed match regexp in a case-insensitive manner.
Test
$ cat file first FiRst FIRST fir3st $ sed 's/[Ff][Ii][Rr][Ss][Tt]/last/g' file last last last fir3st $ sed 's/first/last/Ig' file last last last fir3st GNU sed
sed '/first/Ii This line to be added' file You can try
sed 's/first/somethingelse/gI' if you want to save some typing, try awk. I don't think sed has that option
awk -v IGNORECASE="1" '/first/{your logic}' file For versions of awk that don't understand the IGNORECASE special variable, you can use something like this:
awk 'toupper($0) ~ /PATTERN/ { print "string to insert" } 1' file Convert each line to uppercase before testing whether it matches the pattern and if it does, print the string. 1 is the shortest true condition, so awk does the default thing: { print }.
To use a variable, you could go with this:
awk -v var="$foo" 'BEGIN { pattern = toupper(foo) } toupper($0) ~ pattern { print "string to insert" } 1' file This passes the shell variable $foo and transforms it to uppercase before the file is processed.
Slightly shorter with bash would be to use -v pattern="${foo^^}" and skip the BEGIN block.
Use the following, \b for word boundary
sed 's/\bfirst\b/This line to be added/Ig' file 
