Bash swap String in file with different UUID's

Question

I'm having a custom xml and im trying to replace a multiple occurring string (say "uuidVariable") with a unique UUID each in Bash.

<dict>
    <key>Apple</key>
    <true/>
    <key>uuid</key>
    <string>uuidVariable</string>
</dict>

<dict>
    <key>Banana</key>
    <false/>
    <key>uuid</key>
    <string>uuidVariable</string>
</dict>

I'm able to generate a UUID and store it :

UUID=$(cat /proc/sys/kernel/random/uuid)

But how is it possible to loop through myfile.xml and replace each string with a new UUID?

I know how to count the occurring string, but i don't think this is gonna help me further

countUUID=$(sed 's/uuidVariable/uuidVariable\n/g' myfile.xml | grep -c "uuidVariable")

EDIT: Also i know how to replace 2 strings.. but thats not solving the problem having each unique.

sed -i s/uuidVariable/UUID/g myfile.xml

Likely answered by https://stackoverflow.com/a/39350238/450611 — weirdan, Aug 20 '18 at 14:18

score 3 · Accepted Answer · answered Aug 20 '18 at 15:42

3

I suppose you could do something like this.

awk 'BEGIN { p="/proc/sys/kernel/random/uuid" }
    /uuidVariable/ { getline uuid < p; close(p)
        sub("uuidVariable", uuid) } 1' file.xml >newfile.xml

answered Aug 20 '18 at 15:42

tripleee

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PesaThe · Answer 2 · 2018-08-20T19:31:35.587

Without external utilities, using parameter expansion:

#!/usr/bin/env bash

source=/proc/sys/kernel/random/uuid

while IFS= read -r line; do
    printf '%s\n' "${line//uuidVariable/$(<"$source")}"
done < input > output

Note that this solution will be slow for large input files. Some further reading:

Parameter expansion: wiki.bash-hackers.org, reference manual
Reading a file line-by-line: mywiki.wooledge.org/BashFAQ/001

Bash swap String in file with different UUID's

2 Answers2