CODEWITHSUNDEEP
bashenvsubst
Denys
Denys

Reputation: 4557

Replace value of an environment variable declared in a file

There is a file env.sh, which defines environment variables:

$cat env.sh
export var1=1
export var2=2

I want to replace the value of var1 inside of the file with 3, so that 

$cat env.sh
export var1=3
export var2=2

Is there way to do it without string/regexp matching magic?

I read a lot about envsubst, but still was not able to figure out how to apply it to the task.

Upvotes: 0

Views: 1591

Answers (2)

chepner
chepner

Reputation: 531055

Just use a scriptable editor like ed:

$ cat env.sh
export var1=1
export var2=2
$ printf  '/var1=/s/=.*/var1=3/\nw\n' | ed env.sh
28
28
$ cat env.sh
export var1=3
export var2=2

Upvotes: 2

Cyrus
Cyrus

Reputation: 88583

Without regex in a script:

#!/bin/bash
source env.sh
export var1=3
declare -p var1 > env.sh
declare -p var2 >> env.sh

Output to env.sh:

declare -x var1="3"
declare -x var2="2"

declare -x is synonymous with export.

Upvotes: 3

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