Bash – for loop to get more than one arguments

arraybashvariable

In python and some other programming languages, it is easy to get a vector instead of one variable everywhere and in loops. like python:

for variable in [[user1,pass1],[user2,pass2],[user3,pass3],...]
    print variable[0]
    print variable[1]

But how can I get two arguments in one cycle, in shell?

Best Answer

You might also use an arithmetic for loop like this:

a=(user1 pass1 user2 pass2)
for ((i=0; i<${#a[@]}; i+=2)); do
  echo "${a[i]}: ${a[i+1]}"
done

Related Solutions

Change Parent Shell’s Working Directory Programmatically

make mycd a function so the cd command executes in your current shell. Save it in your ~/.bashrc file.

function mycd {
    if (( $# == 0 )); then
        echo "usage: $FUNCNAME [1|2|3|...]"
        return
    fi
    case $1 in
        1) cd /tmp ;;
        2) cd /a/very/long/path/name ;;
        3) cd /some/where/else ;;
        *) echo "unknown parameter" ;;
    esac
}

Bash – How to print and exit bash if a backtick operator fails

(...) is not (primarily) to group commands, but to start a subshell. So the exit in (echo failed && exit 1) only exits the subshell.

To group commands without running them in a subshell, you'd use { ...; } instead:

X=`getinfo.sh` || {
  echo >&2 "failed"
  exit 1
}

Though here, I'd rather use:

if ! x=$(getinfo.sh); then
  echo >&2 failed
  exit 1
fi

Also note that your echo failed && exit 1 could fail to exit if echo itself fails which could happen for intance when stdout is a file on a full filesystem, or a broken pipe with SIGPIPE ignored, or stdout has been closed, or a file size limit has been reached with SIGXFSZ ignored...

Best Answer

Related Solutions

Change Parent Shell’s Working Directory Programmatically

Bash – How to print and exit bash if a backtick operator fails

Related Question