Bash basics

From Bitpost wiki
Revision as of 20:01, 31 January 2011 by M (talk | contribs)

Bash certainly has its set of snafus.

  • To store commands in variables:
# NOTE don't put spaces around equals sign!
# NOTE don't use ampersands within command strings, they won't work
# use a blank command if needed, that's fine
mycmd1="command param param"
mycmd2="cmd2 param"
if [ -e /myspecialplace ]
mycmd2=""
fi
mycmd3="cmd3 param"
$mycmd1 && $mycmd2 && $mycmd3
  • To capture output
myout=`program1 param`;
  • To check for an error
mkdir "$d2"
if [ $? -gt 0 ]; then
   echo "mkdir error, try that again..."
   exit 3
fi
  • To read input from user
echo "Create the subdirectory?  [$d2]"
if read answer; then
    if [ ${answer} = "y" ] || [ ${answer} = "yes" ]; then
        {whatever}
    else
        {whatever}
    fi
fi