I have a simple text file ./version containing a version number. Unfortunately, sometimes the version number in the file is followed by whitespaces and newlines like
1.1.3[space][space][newline]
[newline]
[newline]
What is the best, easiest and shortest way to extract the version number into a bash variable without the trailing spaces and newlines? I tried
var=`cat ./version | tr -d ' '`
which works for the whitespaces but when appending a tr -d '\n' it does not work.
Thanks, Chris
$ echo -e "1.1.1 \n\n" > ./version
$ read var < ./version
$ echo -n "$var" | od -a
0000000 1 . 1 . 1
0000005
Pure Bash, no other process:
echo -e "1.2.3 \n\n" > .version
version=$(<.version)
version=${version// /}
echo "'$version'"
result: '1.2.3'
I still do not know why, but after deleting and recreating the version file this worked:
var=`cat ./version | tr -d ' ' | tr -d '\n'`
I'm confused... what can you do different when creating a text file. However, it works now.
I like the pure bash version from fgm's answer.
I provide this one-line perl command to remove also other characters if any:
perl -pe '($_)=/([0-9]+([.][0-9]+)+)/'
The extracted version number is trimmed/stripped (no newline or carriage return symbols):
$> V=$( bash --version | perl -pe '($_)=/([0-9]+([.][0-9]+)+)/' )
$> echo "The bash version is '$V'"
The bash version is '4.2.45'
I provide more explanation and give other more sophisticated (but still short) one-line perl commands in my other answer.
