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Just annotations of little "how to's", so I know I can find how to do something I've already done when I need to do it again, in case I don't remember anymore, which is not unlikely. Hopefully they can be useful to others, but I can't guarantee that it will work, or that it won't even make things worse.
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["SOLVED"] Weird failure in bash string comparison

Posted 05-02-2016 at 01:43 AM by the dsc
Updated 05-02-2016 at 01:52 AM by the dsc

A string produced by a given command is somehow different from a string produced by "catting" a file produced by redirecting the output of the very same command. That's weird, if you ask me.

The "solution" is not to compare them both, but create a second file from the "same" redirection, and then strings from "catting" those files. Then the comparison won't always say the strings are different.

Code:
#!/bin/bash
apps=$(ps -axo comm | grep "|firefox\|chromium\|kwrite\|kate\|kcalc\|curl\|wget\|lxterminal\|konsole\|konqueror\|dolphin\|systemsettings5\|mpv\|vlc" )

echo $apps > /dev/shm/appsnow

appsnow=$(cat /dev/shm/appsnow)

prevapps=$(cat /dev/shm/prevapps 2>/dev/null)


echo apps...... \"$apps\"
echo appsnow... \"$appsnow\"
echo prevapps.. \"$prevapps\"

echo


if [[ "$apps" == "$prevapps" ]] ; then

echo same apps comparing vars from different commands

else 

echo different apps comparing vars from different commands

echo $apps > /dev/shm/prevapps

fi




if [[ "$appsnow" == "$prevapps" ]] ; then

echo same apps comparing vars coming from cat

else 

echo different apps comparing vars coming from cat

echo $apps > /dev/shm/prevapps


fi

exit 0
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