Linux String Substitute (sed)

Question :  There is some data on Nautilus App Server 3 in Stratos DC. Data needs to be altered in several of the files. On Nautilus App Server 3, alter the /home/BSD.txt file as per details given below:

a. Delete all lines containing word software and save results in /home/BSD_DELETE.txt file. (Please be aware of case sensitivity)

b. Replace all occurrence of word and to is and save results in /home/BSD_REPLACE.txt file.

Note: Let's say you are asked to replace word to with from. In that case, make sure not to alter any words containing this string; for example upto, contributor etc.

Please Note :-  Perform the below commands based on your question  server,  user name & other details might differ. 

So please read task carefully before executing. 

All the Best 👍

Solution:  

1. Login on   App server as per the task

thor@jump_host ~$ ssh banner@stapp03 The authenticity of host 'stapp03 (172.16.238.12)' can't be established. ECDSA key fingerprint is SHA256:jQBzPUeKPaiyjrpKdy6e4PG/2IswOUaZYIogb7o1SHE. ECDSA key fingerprint is MD5:1f:11:06:a6:ec:6c:f5:37:38:31:79:ad:a6:70:94:37. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'stapp03,172.16.238.12' (ECDSA) to the list of known hosts. banner@stapp03's password: [banner@stapp03 ~]$ sudo su -  We trust you have received the usual lecture from the local System Administrator. It usually boils down to these three things:      #1) Respect the privacy of others.     #2) Think before you type.     #3) With great power comes great responsibility.  [sudo] password for banner: [root@stapp03 ~]#

2. List the existing file and cat the word given in task which need to delete.

[root@stapp03 ~]# ll /home/ total 20 drwx------ 1 ansible ansible 4096 Oct 15  2019 ansible drwx------ 1 banner  banner  4096 Jan 25  2020 banner -rw-r--r-- 1 root    root    9919 Jun 27 12:27 BSD.txt [root@stapp03 ~]# [root@stapp03 ~]# cat /home/BSD.txt |grep software 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. 3. All advertising materials mentioning features or use of this software    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. [root@stapp03 ~]#

Note :- As per the task, BSD.txt file should be intact. But using "sed -i" will change the file in place.So if you want to use "sed -i" , make the copy of the BSD.txt to respective files and do the changes on newly created files.

Another option is which task required is just apply "sed" on original file and redirect the output to respective files. This won't affect the original place. As show below

3. Delete all lines containing word software and save results in /home/BSD_DELETE.txt file

[root@stapp03 ~]# sed '/\<software\>/d' /home/BSD.txt > /home/BSD_DELETE.txt [root@stapp03 ~]# [root@stapp03 ~]# cat /home/BSD_DELETE.txt |grep software [root@stapp03 ~]#

4.  Cat the output for the word which going to replace 

[root@stapp03 ~]# cat /home/BSD.txt |grep and Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. Redistribution and use in source and binary forms, with or without    notice, this list of conditions and the following disclaimer.    notice, this list of conditions and the following disclaimer in the    documentation and/or other materials provided with the distribution. [root@stapp03 ~]#

5.  Now replace  all occurrence of word and redirect to new file

[root@stapp03 ~]# sed 's/\band\b/is/g' /home/BSD.txt > /home/BSD_REPLACE.txt [root@stapp03 ~]#

6.  Validate the word replaced successfully

[root@stapp03 ~]# cat /home/BSD_REPLACE.txt |grep and [root@stapp03 ~]# cat /home/BSD_REPLACE.txt |grep is Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. Redistribution is use in source is binary forms, with or without 1. Redistributions of source code must retain the above copyright    notice, this list of conditions is the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright    notice, this list of conditions is the following disclaimer in the    documentation is/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software    must display the following acknowledgement:    This product includes software developed by the <organization>.    derived from this software without specific prior written permission. [root@stapp03 ~]#

 7. Click on Finish & Confirm to complete the task successful

Happy Learning!!!!

Apart from this if you need more clarity,  I have made a  tutorial video on this , 

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