how to perform multi substitution with sed on a block of text?

Question

I have text file, and in it has a block that has pattern like below:

# cat file
Jit .... enabled=false
Jit ..shoes.. From=2021-01-01
Jit ..gloves.. From=2021-01-01

so I want to change all of these matching regex, wrote a sed file with these lines.

# cat sedfile
/^Jit/ {

    s/enabled=false/enabled=true/g
    s/From=\d+-\d+-\d+/From=2021-02-01/g
}

Pattern /^Jit/ greps lines only starting with Jit and other steps do substitutions. Date can be anything, so I can't hardcode these, therefore matching a pattern is required.

Desired Ouput:

Jit .... enabled=false
Jit ..shoes.. From=2021-01-01
Jit ..gloves.. From=2021-01-01

Thanks! It seems that you wouldn't need the greedy `g` flag, since you are performing one substitution per line. What should be the desired output? — schrodingerscatcuriosity, Oct 05 '21 at 08:05
@schrodigerscatcuriosity global is required, because there are plenty date patterns and all, but I can solve it's complexity, if I get to be sure that pattern is workin with sed substitution, right now it isn't. — Sollosa, Oct 05 '21 at 08:08
Then please [edit] your question and show us an example that accurately represents your file. If there can be more than one date per line, that is a completely different situation. — terdon, Oct 05 '21 at 08:10
Also, what's wrong with your existing solution? The sed script you show should work well if you replace the `\d` with `[0-9]` since `sed` doesn't understand `\d`. — terdon, Oct 05 '21 at 08:13
@terdon ok I updated. [...] symbolizes more text actually, and it doesn't matter in my scenario. — Sollosa, Oct 05 '21 at 08:16
It always matters. What if you have the word `not-enabled=true`? Should that be changed? But anyway, since you still only show one pattern per line, it looks like you don't need `g` which is only useful if you want to make multiple substitutions on the same line. — terdon, Oct 05 '21 at 08:18

terdon · Accepted Answer · 2021-10-05T08:38:54.153

2

Sed doesn't know about \d. Just use the standard [0-9] character class instead:

$ cat sedfile
/^Jit/ {

    s/enabled=false/enabled=true/
    s/From=[0-9]+-[0-9]+-[0-9]+/From=2021-02-01/
}

Then you can do:

line1
Jit .... enabled=false
Jit .... From=2021-01-01
line4

$ sed -Ef sedfile file
line1
Jit .... enabled=true
Jit .... From=2021-02-01
line4

Or, without a script file:

$ sed -E '/^Jit/{s/enabled=false/enabled=true/; s/From=[0-9]+-[0-9]+-[0-9]+/From=2021-02-01/}' file
line1
Jit .... enabled=true
Jit .... From=2021-01-01
line4

I removed the g modifier since you only seem to have one occurrence of the pattern per line.

edited Oct 05 '21 at 08:38

answered Oct 05 '21 at 08:16

terdon

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Ok amigo, you did not update date regex in oneliner. – Sollosa Oct 05 '21 at 08:34
1

Whoops. Sorry @Sollosa, fixed now. – terdon Oct 05 '21 at 08:39

score 1 · Answer 2 · answered Oct 05 '21 at 08:36

I propose a solution assuming (until more comprehensive sample input) that the lines have strict end patterns. If that's the case it wouldn't be necessary more complex matching.

/^Jit/{
  s/false$/true/
  s/[0-9\-]\+$/2021-02-01/
}'

Output:

Jit .... enabled=true
Jit .... From=2021-02-01

About the removed g flag, see @terdon's answer.

how to perform multi substitution with sed on a block of text?

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