sed usage details

sed usage

1, replace symbols:

sed -e 's#/#-#g' -e's#:#-#g' passwd

2, use sed file input command:

vim 123.sed
s#:#/#g
s#/#-#g

sed -f 123.sed passwd

3, print:

sed -n 2p passwd

4 ,Replace the nth match:

sed 's/in/AAAAA/2' passwd

root:x:0:0:root:/root:/bin/bashbin:x:1:1:bAAAAA:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbAAAAA/nologin

Note: Only when in is matched for the second time in each line will it be replaced with AAAAA

5. Replace the mth match in the nth line:

sed '2s/in/AAAAA/2' passwd

root:x:0:0:root:/root:/bin/bashbin:x:1:1:bAAAAA:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbin/nologin

Note: You can use the -n -p combination

sed -n '2s/in/AAAAA/2p' passwd 
bin:x:1:1:bAAAAA:/bin:/sbin/nologin

sed -n '2,3s/in/AAAAA/2p' passwd

bin:x:1:1:bAAAAA:/bAAAAA:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbAAAAA/nologin

sed -n '2,$s/in/AAAAA/2p' passwd

Note: You can use $ to indicate the end

6 and save the replacement result to the file:

sed -n '2s/in/AAAAA/2pw passwd.sed' passwd 
bin:x:1:1:bAAAAA:/bin:/sbin/nologin

cat passwd.sed 
bin:x:1:1:bAAAAA:/bin:/sbin/nologin

7, back up the replacement result, and modify the source file:

sed -i.bak '2s/in/AAAAA/2' passwd

cat -n  passwd1	root:x:0:0:root:/root:/bin/bash2	bin:x:1:1:bAAAAA:/bin:/sbin/nologin

ls passwd*passwd  passwd.bak

8, conditional filter modification:

sed -n '/root/s/bin/AAAAA/p' passwd

root:x:0:0:root:/root:/AAAAA/bashoperator:x:11:0:operator:/root:/sAAAAA/nologin

9, sed multi-command execution:

sed  '1{s/root/ROOT/s/bin/BIN/
}' passwd

ROOT:x:0:0:root:/root:/BIN/bash

sed -n -e '1s/root/ROOT/' -e '1s/bin/BIN/' -e 1p passwd

ROOT:x:0:0:root:/root:/BIN/bash

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