I always feared shell scripts when I was in college. Always knew that it is very powerful if I use it properly, I never did.
Two days back, in I was trying to help one of my college junior to setup Qt4 and the environment to run it. I told him to follow this page. But Pradeepto said the idea of having another user is not so good. and he said:
Apr 30 00:48:21 pradeepto: you can even do make sure that as you changedirectories,
the env-vars are set automagically.So, I tried to something like that, asked few questions on #bash about how to write a function with same name of a shell command and then call the actual shell command. So, got the shell-builtin-command ‘builtin’ which executes other shell builtins. Also asked lots of questions to Jace about shell programming :p
My target was, as I change my directory to any directory named ‘pyqt4’ or sub-directories under it all environment variables should change accordingly to run Qt4 or PyQt4 codes and in other directories the normal environment should stay to run Qt3 :)
The result in my .bashrc :
export tQTDIR=“$QTDIR”export tPATH=“$PATH”
export tMANPATH=“$MANPATH”
export tLD_LIBRARY_PATH=“$LD_LIBRARY_PATH”
export tPKG_CONFIG_PATH=“$PKG_CONFIG_PATH”
export tQTINC=“$QTINC”
export tQTLIB=“$QTLIB”
export eFlag=0changePath()
changePath()
{QTDIR=“$tQTDIR”
PATH=“$tPATH”
MANPATH=“$tMANPATH”
LD_LIBRARY_PATH=“$tLD_LIBRARY_PATH”
PKG_CONFIG_PATH=“$tPKG_CONFIG_PATH”
QTLIB=“$tQTLIB”
QTINC=“$tQTINC”
export QTDIR PATH MANPATH LD_LIBRARY_PATH PKG_CONFIG_PATH QTINC QTLIB
}
cd ()
{
if [ “$#” -eq “0” ]
then
if [ “$eFlag” -eq “1” ]
then
changePath
export eFlag=0
fi
builtin cd
else
bname=echo "$1"|grep pyqt4
if [ “${bname}” = “$1” ]
then
QTDIR=/home/kdedev/src/kde/qt-copy
PATH=$QTDIR/bin:$PATH
MANPATH=$QTDIR/doc/man:$MANPATH
LD_LIBRARY_PATH=$QTDIR/lib:$LD_LIBRARY_PATH
PKG_CONFIG_PATH=$QTDIR/lib/pkgconfig:$PKG_CONFIG_PATH
QTINC=$QTDIR/include
QTLIB=$QTDIR/lib
export QTDIR PATH MANPATH LD_LIBRARY_PATH PKG_CONFIG_PATH QTINC QTLIB
export eFlag=1
builtin cd “$1”
else
if [ “$1” = “..” ]
then
builtin cd “$1”
dname=pwd
bname=echo "$dname"|grep pyqt4
if [ “$bname” != “$dname” ]
then
if [ “$eFlag” -eq “1” ]
then
changePath
export eFlag=0
fi
fi
else
if [ “$eFlag” -eq “1” ]
then
changePath
export eFlag=0
fi
builtin cd “$1”
fi
fi
fi
}
I think the code is not so much readable in my blog :)
Update: Pradeepto asked me to upload the code as a file, so here it is. Just copy paste the contents of this file into your $HOME/.bashrc .