sed command to replace a value in config file

Question

I am using this command:

sed -i  's/\(^TestT_STOA_TS1901=\).*/\1N/'/app/test/must/untuio.cf

And I am getting this error:

XXXXXXXXX:/app/test/must>sed -i  's/\(^TestT_STOA_TS1901=\).*/\1N/'/app/test/must/untuio.cf
sed: -e expression #1, char 33: unknown option to `s'

Why is this happening? How can I replace a value in a config file?

Solution 1

Use sed:

sed -i 's/\(^Key2=\).*/\1Value4/' file

The -i flag activates seds in-place editing. It searches for a line that begins with Key2= and replaces the line with the key (\1) followed by the new value Value4.

Edit:

If you have slashes or other command characters used in sed, you have to escape them:

sed -i 's/\(^Key2=\).*/\1long\/value\'/with\$many\"strange\^characters/' /path/to/file

Edit 2: In your case:

sed -i  's/\(^TestT_STOA_TS1901=\).*/\1N/' /app/test/must/untuio.cf

Solution 2

Couple of ways :

1. Probably the most straight forward way, matching the appropriate key by /Key2/ and then replacing Value2 with Value4 :

   $ sed '/Key2/ s/Value2/Value4/' foo.txt 
   Key1=Value1            
   Key2=Value4          
   Key3=Value3
   

2. If you know that the digits will come at last and if you just want to replace those digit(s) with something else (here replacing 2 with 4) :

   $ sed '/Key2/ s/[[:digit:]]\+$/4/' foo.txt 
   Key1=Value1
   Key2=Value4
   Key3=Value3
   

I also have some other ways on top of my head but they depends on your use case. Let us know if these would suffice.

Your mistakes in sed -i -e '/KEY=/ s/= .*/= new_value/' /path/to/file :

• As per your example, no Key will be matched with /KEY=/ as it is not in proper cases and there is a number after Key and = is after that

• s/= .*/= new_value/, from your example there is no space after = but your pattern-substitution seems it has a space in the actual file. Otherwise as far as your given example is concerned there is no space after =.

Solution 3

Using awk? =)

awk -F= '$1=="Key2" {printf "%s=%s\n",$1,"Value4"; next}1' your_input_file

---

Example

The input file foo

cat foo

Key1=Value1            
Key2=Value2          
Key3=Value3

The command output

% awk -F= ' $1=="Key2" {printf "%s=%s\n",$1,"Value4"; next}1' foo
Key1=Value1            
Key2=Value4
Key3=Value3

Comments

[canonical]

sed -i 's/(^Key2=).*/\1Value4/' file...this didnt work

[chaos]

@canonical Use the exact command as in my answer. I used backslashes before the brackets.

[canonical]

i get this error : sed: -e expression #1, char 33: unknown option to `s'

[chaos]

@canonical Has the string you want to replace slashes / in it? (Value4 in the example). If yes, you need to escape them: sed -i 's/\(^Key2=\).*/\1value\/to\/replace/' file. Or post the exact command you entered.

[canonical]

this is the exact command i used sed -i 's/(^TestT_STOA_TS1901=).*/\1N/'/app/test/must/untui‌​o.cf I am somehow missing the blackslash when pasting here.But i am actually using it

[chaos]

@canonical See the edit of my answer. Else we need the exact command and error. Post it in your question or between backticks or see askubuntu.com/editing-help

[fedorqui]

Note you can also say awk 'BEGIN{FS=OFS="="} $1=="Key2" {$2="Value4"}1' file so you don't have to "next".

[canonical]

I edited the question now

[chaos]

@canonical Use this: sed -i 's/\(^TestT_STOA_TS1901=\).*/\1N/' /app/test/must/untuio.cf. After between the sed command and the file must be a space, else it is interpreted as command, and therefore spits an error.

[A.B.]

@canonical If you like my answer, just click the little grey ☑ on the left hand site of my answer now turning it into beautiful green. If you do not like my answer, click on the little grey down-arrow below the 0, and if you really like my answer, click on the little grey checkmark and the little up-arrow... If you have any further questions, go to askubuntu.com/questions/ask