Linux sed commands

the samples text file

[root@localhost /]# cat /home/sed.txt
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Replace word

sed ‘s/python/go/’ /home/sed.txt
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only the first ‘python’ is replaced with ‘go’ for each line .

use ‘g’ to replace for all

sed ‘s/python/go/g’ /home/sed.txt
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what if only replace 2nd ‘python’ with ‘go’ for each line

sed ‘s/python/go/2’ /home/sed.txt
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what if only substitute the last line ? (or pass in 5)

sed ‘$ s/python/go/g’ /home/sed.txt
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linux is friendly to developer
grep sed and awk is useful to processing text
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replace a range of lines (with g option to replace all occurrence in each line )

[root@localhost /]# sed ‘2,3 s/python/go/g’ /home/sed.txt
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linux is friendly to developer
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use -n option to only print out the modified lines (add p at end)

[root@localhost /]# sed -n ‘s/python/go/gp’ /home/sed.txt
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delete nth line

sed ‘3d’ /home/sed.txt
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or delete a range of lines

[root@localhost /]# sed ‘1,3d’ /home/sed.txt
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delete the matched lines

[root@localhost /]# sed ‘/python/d’ /home/sed.txt
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insert line after matching line

sed ‘/languages/a ++’ /home/sed.txt
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python php c java are programming languages
++
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add chars after matching keyword (without new line), use & as the matching word

sed ‘s/python/& language/’ /home/sed.txt
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use -i option to apply changes (insert, replace, delete) in place

[root@localhost /]# sed -i ‘s/python/& script/g’ /home/sed.txt
[root@localhost /]# cat /home/sed.txt
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Write output to file

$ cat data11.txt
python, php
linux, windows
c, python
$ sed -n '/python/w py.txt' data11.txt
$ cat py.txt
python, php
c, python

1–1 char mapping

cat data.txt
echo 1.
echo 2.
echo 3.
echo 4.
echo 1 again.
sed 'y/123/789/' data8.txt
echo 7.
echo 8.
echo 9.
echo 4.
echo 7 again.

read data from file1 into file2 at the n-th line in file2

cat data1.txt
1
2
cat data2.txt
a
b
sed '3r data1.txt' data2.txt
a
b
1
2
c