how to check if a file exist using adb shell

Question

I have a bash script which goes as follows

if [ -f "/sdcard/testfile"]
then 
echo "exists" > /sdcard/outfile
else
echo "does not exist" > /sdcard/outfile
fi

I have sufficient permission to run this with /system/bin/sh. I am calling this script from my application and running this with /system/bin/sh. But after running I am getting false, even if the file '/sdcard/testfile' is there. When I am explicitly running in adb shell, I am getting this error

[: not found

Is there any other way to accomplish this task? I cannot just use java.io.File because of permission issue of application; therefore, I am adhering to shell script (command).

I need the output in the application itself. I mean,

if(filesAreAvailable)
    executeSomething();
else
    executeSomethingElse();

Basically I am programmatically writing this script in the /data/data/myPackageName/files directory and for calling the command:

if [ -f "/sdcard/testfile"]

as

fileWriterScript.write("if [ -f \"/sdcard/testfile\" ]\n")

Answer 1

When using test, you need a space after the opening bracket and before the closing bracket.

From man test:

SYNOPSIS
    test expression
    [ expression ]

So change:

[ -f "/sdcard/testfile"]

to:

[ -f "/sdcard/testfile" ]

Answer 2

If you need to use this in bash script then you can do it that way:

if [[ `adb shell ls /sdcard/path/to/your.file 2> /dev/null` ]]; then
    echo "File exists";
else
    echo "File doesn't exist";
fi

Answer 3

you could do a ls and then check the output - when it contains "No such file or directory" - the file is not there. But still IMHO you need the permission