0

First things first, here's the code:

# build.prop Tweaks
FILE=/system/build.prop
#Properties to change Array
PROPARR=('net.tcp.buffersize.default' 'net.tcp.buffersize.wifi' 'net.tcp.buffersize.umts' 'net.tcp.buffersize.gprs' 'net.tcp.buffersize.edge' 'wifi.supplicant_scan_interval' 'ro.HOME_APP_ADJ' 'dalvik.vm.dexopt-flags' 'dalvik.vm.execution-mode' 'dalvik.vm.heapstartsize' 'dalvik.vm.heapgrowthlimit' 'dalvik.vm.heapsize' 'dalvik.vm.heaptargetutilization' 'dalvik.vm.heapminfree' 'dalvik.vm.heapmaxfree' 'debug.sf.hw');
#Property Values
PROPVALARR=('4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '300' '1' 'm=y,v=n,o=v,u=n' 'init:jit' '16m' '128m' '512m' '0.75' '12m' '16m' '1');
# this variable is just a place holder for the future line number of the prop values
lineNum=
# Loop through the properties I want to change
for i in $PROPARR; do

prop=$PROPARR($i);
arg=$PROPVALARR($i);
if grep -Fq $prop $FILE ; then
        lineNum=`sed -n "/${prop}/=" $FILE`;
        sed -i "${lineNum} c${prop}=${arg}" $FILE;
else
        echo $prop=$arg >> $FILE;
fi;

done;

Now, orignally in the loop I was accessing the array like this: prop=$PROPARR[$i]; arg=$PROPVALARR[$i];

but it was writing weird code to the end of build.prop, and it was only the 1st item in the array(s)

So, then I tried it like I posted, and now I am getting a syntax error near unexpected token '('

So with the first issue that I was having, I feel it is safe to assume that #1 the loop isn't correctly written, #2 the text I am attempting to write is incorrectly written, #3 is the proper way to access the items

So the question is, how can I fix this so the loop loops correctly through the array, and writes the proper lines to build.prop (or updates the line if found)

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  • Define yourself an array array=(hello world) and 1. print the second element, 2. loop over and print each element. When you're not familiar with a language, it really helps to start small and fixing one error at a time rather than writing a complete program and then trying to fix everything at once. Commented Jun 26, 2014 at 17:23

2 Answers 2

Reset to default
1

There was some problems with how you were referencing the array values. The following code should work.

# build.prop Tweaks
FILE=/System/build.prop
 #Properties to change Array
PROPARR=('net.tcp.buffersize.default' 'net.tcp.buffersize.wifi' 'net.tcp.buffersize.umts' 'net.tcp.buffersize.gprs' 'net.tcp.buffersize.edge' 'wifi.supplicant_scan_interval' 'ro.HOME_APP_ADJ' 'dalvik.vm.dexopt-flags' 'dalvik.vm.execution-mode' 'dalvik.vm.heapstartsize' 'dalvik.vm.heapgrowthlimit' 'dalvik.vm.heapsize' 'dalvik.vm.heaptargetutilization' 'dalvik.vm.heapminfree' 'dalvik.vm.heapmaxfree' 'debug.sf.hw');
 #Property Values
PROPVALARR=('4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '300' '1' 'm=y,v=n,o=v,u=n' 'init:jit' '16m' '128m' '512m' '0.75' '12m' '16m' '1');
 # this variable is just a place holder for the future line number of the prop values
lineNum=
 # Loop through the properties I want to change
for i in ${!PROPARR[@]}; do
    prop=${PROPARR[$i]};
    arg=${PROPVALARR[$i]};
    if grep -Fq $prop $FILE ; then
        lineNum=`sed -n "/${prop}/=" $FILE`;
        sed -i "${lineNum} c${prop}=${arg}" $FILE;
    else
        echo $prop=$arg >> $FILE;
    fi;
done;

Edit: Ok you need some changes to your sed statements as well. Also to write /System/ you will need root permissions. Here is the updated code:

# build.prop Tweaks
FILE=/System/build.prop
#Properties to change Array
PROPARR=('net.tcp.buffersize.default' 'net.tcp.buffersize.wifi' 'net.tcp.buffersize.umts' 'net.tcp.buffersize.gprs' 'net.tcp.buffersize.edge' 'wifi.supplicant_scan_interval' 'ro.HOME_APP_ADJ' 'dalvik.vm.dexopt-flags' 'dalvik.vm.execution-mode' 'dalvik.vm.heapstartsize' 'dalvik.vm.heapgrowthlimit' 'dalvik.vm.heapsize' 'dalvik.vm.heaptargetutilization' 'dalvik.vm.heapminfree' 'dalvik.vm.heapmaxfree' 'debug.sf.hw');
#Property Values
PROPVALARR=('4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '4096,87380,256960,4096,16384,256960' '300' '1' 'm=y,v=n,o=v,u=n' 'init:jit' '16m' '128m' '512m' '0.75' '12m' '16m' '1');
# this variable is just a place holder for the future line number of the prop values
# Loop through the properties I want to change
for i in ${!PROPARR[@]}; do
    prop=${PROPARR[$i]};
    arg=${PROPVALARR[$i]};
    if grep -Fq $prop $FILE ; then
        sed -i.bak s/$prop.*/$prop=$arg/ $FILE;
    else
        echo $prop=$arg >> $FILE;
    fi;
    echo "$prop $arg"
done;

It is also worth noting that the -i option to the sed statement will be overwritten with every iteration of the for loop. So you won't have a backup of the original after running this script. Perhaps manually take a backup before running the script or add it in as part of it.

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4 Comments

ok, no more errors, however it's not writing the changes to build.prop
I will try your edit. Not worried about backing up, and yeah this needs root anyways, due to this happenning during the flashing of a mod in a custom recovery :)
YIKES! now instead of modyfing a exiting property it is appending to it... for instance: dalvik.heapstartsize=16m=16m is what I am ending up with
Did you run the script on the file twice? That would end up with a double append. OK we can fix that too. Modify the line "sed -i.bak s/$prop/$prop=$arg/ $FILE;" to be "sed -i.bak s/$prop.*/$prop=$arg/ $FILE;". That should fix things. I've edited the post - the second script has the additional pattern match now.
1

A better solution, cleaner and more readable, that leverages associative arrays, a feature built-in in Bash.

declare -A PROPERTIES
PROPERTIES['net.tcp.buffersize.default']="4096,87380,256960,4096,16384,256960"
PROPERTIES['net.tcp.buffersize.wifi']="4096,87380,256960,4096,16384,256960"
PROPERTIES['net.tcp.buffersize.umts']="4096,87380,256960,4096,16384,256960"
PROPERTIES['net.tcp.buffersize.gprs']="4096,87380,256960,4096,16384,256960"
PROPERTIES['net.tcp.buffersize.edge']="4096,87380,256960,4096,16384,256960"
PROPERTIES['wifi.supplicant_scan_interval']=300 
PROPERTIES['ro.HOME_APP_ADJ']=1 
PROPERTIES['dalvik.vm.dexopt-flags']=m=y,v=n,o=v,u=n
PROPERTIES['dalvik.vm.execution-mode']=init:jit
PROPERTIES['dalvik.vm.heapstartsize']=16m
PROPERTIES['dalvik.vm.heapgrowthlimit']=128m
PROPERTIES['dalvik.vm.heapsize']=512m
PROPERTIES['dalvik.vm.heaptargetutilization']=0.75 
PROPERTIES['dalvik.vm.heapminfree']=12m
PROPERTIES['dalvik.vm.heapmaxfree']=16m
PROPERTIES['debug.sf.hw']=1

# Loop through the properties I want to change
for prop in ${!PROPERTIES[@]}; do

  arg=${PROPERTIES["$prop"]}
  echo $prop = $arg

done;

In this snippet I'm just focusing on how to loop over an associative array. You should be able to hook your own logic into the loop.

For a full reference:

http://www.gnu.org/software/bash/manual/bashref.html#Arrays

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3 Comments

declare -A: invalid option and am getting syntax error: invalid arithmetic operator (error token is ".tcp.buffersize.default") where the .tcp.buffersize.default changes for each line, but it happens for each line
:( no associative arrays supported in your bash version
apparently not. I know there is for Linux, but I'm sure bash for Android is crippled

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