Bash help, extracting variables from text file

[CaptainMark]

This is probably simple for most here but I'm still learning so please be patient.

I have a script that I've been practising on for a while, which stores some basic settings just in a text file and my script will read the variables from the text to remember them from last time, here it is currently:


if [ -e $targets ]; then
read source destination < $targets
else .....

The variable $targets contains the location of the text file so this part takes the first two words from the text file and assigns them as the variables $source and $destination (which are also file paths) my problem is that I want to change it so its the first two lines that get assigned to variables not the first two words, so if the $source and $destination can contain spaces.

I thought this would work


if [ -e $targets ]; then
IFS=$'\n'
read source destination < $targets
unset IFS
fi
the first variable comes out as expected the complete first line of the text file including spaces, however the second variable does not read the second line but comes out blank.

Could someone help me realise my mistake and point out what I'm missing so I can correct my script,
Thanks
Mark

[TheFu]

I think you are making this harder than it needs to be. If I understand correctly, that is.

Suppose you have 2 files -
a) shell script - called "prg"
b) settings - called "settings"

Inside "settings" file:

source=/some/path/to/a/file/or/directory
target=/some/other/pathBack inside the "prg" file:

if [ -f "settings" ] ; then
source "settings"
fi This will set the environment variables for the "settings" file and make them available to the "prg" when running.

Almost anything we could want to accomplish is well explained with examples in the "Advanced Bash Scripting Guide" - http://tldp.org/LDP/abs/html/ Here's a link for a multi-line read example: http://tldp.org/LDP/abs/html/internal.html#READR

I'm pretty certain there is a way to read specific settings from a file 1 at a time, if you like, but I wouldn't do it the way you are attempting. These are not Windows ini files, after all. I'd do it by using grep to get the specific line out that I wanted - it would need to be a fairly complex regex to handle comments (#) properly and dump anything after the value. My initial solution lets the bash interpreter handle that issue for us.

[sisco311]

+1 for TheFu's idea.

Save the filenames in a file:


cat << EOF > files
source="$source"
dest="$dest"
EOF

Then simply source it in your script:

. files

Otherwise you need two read commands:


{
read -r source
read -r dest
} < filename


But file names may contain newlines in which case your script will fail. You have to use the null character to separate the filenames:


printf '%s\0' "$source" "$dest" > files



{
IFS= read -r -d '' source
IFS= read -r -d '' dest
} < files

[CaptainMark]

thanks very much, ill study these ideas. i dont have to worry but these variables containing new lines but its about learning so ill be taking this on board, thanks