Berkeley CSUA MOTD:Entry 19911
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2025/07/10 [General] UID:1000 Activity:popular
7/10    

2000/11/26-28 [Computer/SW/Unix, Computer/SW/Languages] UID:19911 Activity:moderate
11/25   #!/bin/sh
        : How do I make bourne shell subroutine modify a global variable?
        : Want to use VAR1 and VAR2 after the subroutine parses my_input_file
        foo() {
        while read VAR1 VAR2
        do
          echo "Reading $VAR1 and $VAR2"
          export VAR1 VAR2
        done < my_input_file
        export VAR1 VAR2
        }
        foo
        echo VARS = $VAR1 , $VAR2 # VAR1 & VAR2 are blank/empty-strings!
        \_ while loop is executed in a separate shell in bourne shell,
           thus its not possible.
           \_ wrong. but the order is backwards. Try this.
              #!/bin/sh
              export GLOBALVAR
              GLOBALVAR=1
              change(){
                GLOBALVAR=2
              }
              change
              echo $GLOBALVAR
                     \_ too complicted:
                           #!/bin/sh
                           change() {
                              GLOBAL=2;
                           }
                           GLOBAL=1;
                           echo GLOBAL is $GLOBAL
                           change
                           echo GLOBAL is $GLOBAL

                  \_ uh, no you are wrong. In *bourne* shell (virutally
                     unchanged since AT&T UNIX Version 7) while loops
                     are a separate process (I'm looking at the code
                     right now) when the input or output of the shell
                     is redirected. To avoid this you need to use exec
                     to save and restore STDIN. Try something like:
                     #!/bin/sh

                     myfunc () {
                       exec 5<&0 < "$1";
                       while read LINE ;
                       do
                          COUNT=`echo $COUNT + 1 | bc`
                       done
                       exec 0<&5 5<&-
                    }

                    COUNT=0
                    echo COUNT is $COUNT
                    myfunc /etc/passwd
                    echo COUNT is $COUNT
        \_ Get new shell.
           \_ Stick with Bourne shell as Steve and GOD intended.
ERROR, url_link recursive (eces.Colorado.EDU/secure/mindterm2) 2025/07/10 [General] UID:1000 Activity:popular
7/10    

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