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Sed command to replace text

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thierryR51 Posted messages 144 Status Membre -  
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   -
Hello,
I'm trying to replace an IP in the hosts file 
cat /etc/hosts
80.119.80.108 Backup


I tried this: 
sed -e "s/Backup/80.119.80.109 Backup/g" -i /etc/hosts;


But the result I get is this; 
80.119.80.108 80.119.80.109 Backup

I wanted to remove 80.119.80.108 but I'm stuck in the sem....... I'm almost there, but a little help would be appreciated.
Thank you

Configuration: Mageia5 on Toshiba Satellite L350

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4 réponses

Réponse 1 / 4
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500
 
Hello; 

sed -i.bak '/Backup/{s/^[^ ]*/80.119.80.109/}' /etc/host
s

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1
thierryR51 Posted messages 144 Status Membre 8
 
If I embed it in my script with variables 
sed -i.bak '/'$nameServeur'/{s/^[^ ]*/'$newIp'/}' /etc/hosts

I get an error about the first character. 
sed -i.bak / 'MaMaison/{s/^[^ ]*/86.66.183.203/}' /etc/hosts
sed: -e expression no. 1, character 1: unfinished regular expression address

It seems to me that I wrote it correctly....
0
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500 > thierryR51 Posted messages 144 Status Membre
 
There is an extra space in the name of your variable $nameServeur ;-( 

/ 'MaMaison/


$ name=" Sauvegarde";nip="80.119.80.109"

$ sed '/'${name}'/{s/^[^ ]*/'${nip}'/}' plop 
sed: -e expression n°1, character 1: incomplete address regular expression

$ name="Sauvegarde";nip="80.119.80.109"

$ sed '/'${name}'/{s/^[^ ]*/'${nip}'/}' plop 
80.119.80.109 Sauvegarde
0
thierryR51 Posted messages 144 Status Membre 8
 
Thank you Zipe31. I can't stop thanking you... It's going to get boring eventually. ;)
0
thierryR51 Posted messages 144 Status Membre 8
 
However, I did what was necessary to avoid having this blank 
nameServeur=${Serveurname%% }

but it is still there.
0
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500 > thierryR51 Posted messages 144 Status Membre
 
What does the starting variable ${Serveurname} look like?
0
Réponse 2 / 4
thierryR51 Posted messages 144 Status Membre 8
 
Thank you Zipe31. You're still the great bash specialist...
Have a good evening.

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0
thierryR51 Posted messages 144 Status Membre 8
 
1 line of hosts is broken down as follows: 
IP + TAB + hostname

I think the whole problem is about inserting the TAB.
It seems that there are several SED versions and not all of them handle '\t'
http://sed.sourceforge.net/sed1line_fr.html
0
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500 > thierryR51 Posted messages 144 Status Membre
  
sed '/Backup/{s/[^\t]*/80.119.80.109/}' /etc/hosts
0
thierryR51 Posted messages 144 Status Membre 8
 
I adapted it to my variables. In fact, it writes nothing. I only have the proofreading of my file. 
sed '/'${nameServeur}'/{s/^[^\t]*/'${newIp}'/}' $filehosts

or $nameServeur = MaMaison
$newIp=80.119.80.109
$filehosts= /etc/hosts

Is it because the line containing 'MaMaison' no longer exists in my file?

In fact, I would like:
If the line exists: Replace it
If it does not exist: Create it.

Thank you for your help. The sed command is complicated...
0
UnGnU Posted messages 1468 Status Contributeur 158 > thierryR51 Posted messages 144 Status Membre
 
Hello,

An example of a hosts file without the entry MaMaison 
$ cat my_hosts_file
80.119.80.108 Backup

An example with both entries 
$ cat my_home_file
80.119.80.108 Backup
192.168.10.1 MaMaison

The script file for sed : 
$ cat script.sed
/Backup/{
s/[^\t]*/80.119.80.109/
}

/MaMaison/{
s/[^\t]*/192.168.10.2/
b
}

$ {
a\192.168.10.2\tMaMaison
}


The script executed on the file without the occurrence of MaMaison : 
$ sed -f script.sed my_hosts_file
80.119.80.109 Backup
192.168.10.2 MaMaison


The script executed on the file already having both occurrences 
$ sed -f script.sed my_home_file
80.119.80.109 Backup
192.168.10.2 MaMaison
0
thierryR51 Posted messages 144 Status Membre 8
 
OK, I see that with sed the solution exists. So to integrate this into my script, I did this. I don't have a second sed file. I'm integrating everything into my script. 
sed -e '/'${nameServeur}'/{s/^[^\t]*/'${newIp}'/}';$ '{a\'${newIp}'\t'${nameServeur}'}' $filehosts

The return of the command is 
+ sed -e '/MaMaison/{s/^[^\t]*/86.66.183.130/}'


^C

As you can see, it's blocking. I had to terminate the script manually. Apparently, the ";" doesn't seem to be taken into account. Yet I followed the advice from https://openclassrooms.com/courses/la-commande-sed where they clearly state that for a single-line command, we separate with ";"

Did I misunderstand?
0
Réponse 3 / 4
thierryR51 Posted messages 144 Status Membre 8
 
Little problem. When sed wants to write 

 sed -i -e '/MyHouse/{s/^[^\t]*/86.66.183.119/}' -e b -e '$ a\86.66.183.119\tMyHouse' /etc/hosts

and the line does not exist in the hosts file, it doesn't write anything.

I can see that b is without the ' but in the script, they are there. It's in the result of the command that they disappear. I replaced the ' with " but that didn't work either. Could that be the cause of the non-writing?
Thank you.

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0
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500
 
Hello,

Try it like this: 
sed -i -e '/MyHouse/{s/^[^\t]*/86.66.183.119/;b}' -e '$ a\86.66.183.119\tMyHouse' /etc/hosts
0
Réponse 4 / 4
thierryR51 Posted messages 144 Status Membre 8
 
Indeed, post 29 also mentions the same thing and I had replied to you afterwards. It works but not well. Maybe we need to make 2 sed lines with an "if" condition?

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0
zipe31 Posted messages 34620 Registration date   Status Contributeur Last intervention   6 500
 
However...

The entry "MaMaison" does not exist and is added: 
$ cat hosts 
80.119.80.108 Backup

$ sed -e '/MaMaison/{s/^[^\t]*/86.66.183.119/;b}' -e '$ a\86.66.183.119\tMaMaison' hosts 
80.119.80.108 Backup
86.66.183.119 MaMaison


The entry "MaMaison" exists and is modified: 
$ cat maison 
80.119.80.108 Backup
192.168.10.1 MaMaison

$ sed -e '/MaMaison/{s/^[^\t]*/86.66.183.119/;b}' -e '$ a\86.66.183.119\tMaMaison' maison 
80.119.80.108 Backup
86.66.183.119 MaMaison
0