korn shell: dynamic use of here docs

[support_billa]

Hello,

I have following issue :

I use in a shell script an oracle command ( RMAN ). i use the RMAN command by using the EOF execution method like below.
but the part of the channels should by dynamic. how can i create the EOF part dynamic ? with a temporary file ?

the input should be the number of channels and depend of the nummer i should create dynamic channels in the EOF part


NOW:
rman <<-EOF
connect catalog rman/${RMAN_CONNECT}@${RMAN_SID}
connect target  /
run {
   allocate channel dev_1 type 'SBT_TAPE';
...
...
   release channel dev_1;
}
EOF

NEW:
nr_channels=3  # so 3 channels should be exist in the EOF part

# create the dynamic part of channels
rman <<-EOF
connect catalog rman/${RMAN_CONNECT}@${RMAN_SID}
connect target  /
run {
   allocate channel dev_1 type 'SBT_TAPE';
   allocate channel dev_2 type 'SBT_TAPE';
   allocate channel dev_3 type 'SBT_TAPE';
...
...
   release channel dev_3;
   release channel dev_2;
   release channel dev_1;
}
EOF

regards

[Dennis Handly · Accepted solution]

>i use the RMAN command by using the EOF execution method

(These are called here documents or here docs.)

>how can i create the EOF part dynamic? with a temporary file?

Whatever is easiest and can be understood and maintained.

A separate file with echo and cat may be easiest.  But you can put scripts into the here doc:

rman <<-EOF
connect catalog rman/${RMAN_CONNECT}@${RMAN_SID}
connect target  /
run {

$(

for i in dev_1 dev_2 dev_3; do

   echo "   allocate channel $i type 'SBT_TAPE';"

done

)

...

$(

for i in dev_3 dev_2 dev_1; do

   echo "   release channel $i;"
done

)

}
EOF

But it may be easier to just create a temp file:

tmp_file=/var/tmp/tf.$$

{

cat <<-EOF1

connect catalog rman/${RMAN_CONNECT}@${RMAN_SID}
connect target  /
run {

EOF1

for i in dev_1 dev_2 dev_3; do

   echo "   allocate channel $i type 'SBT_TAPE';"

done

cat <<-EOF2

...

EOF2

for i in dev_3 dev_2 dev_1; do

   echo "   release channel $i;"
done

cat <<-EOF3

}

EOF3

} > $tmp_file

rman < $tmp_file

rm -f $tmp_file  # cleanup

[support_billa]

hello,

i prefer option 1, but option 2 is also an alternative.

here my solution :

NR_CHANNELS=3  # define number of channels, starts with "0"
i=0
(( ii = NR_CHANNELS - 1 ))

rman <<-EOF
..
#  allocate channel : dynamic part
#  allocate channel dev_0 type 'SBT_TAPE';
$( 
while [ ${i} -lt ${NR_CHANNELS} ]; do
  echo "allocate channel dev_${i} type 'SBT_TAPE';"
  (( i += 1 ))
done
)
#  release channel : dynamic part
#  release channel dev_0;
$( 
until [ ${ii} -lt 0 ]; do
  echo "release channel dev_${ii};"
  (( ii -= 1 ))
done
)
}
EOF

last question :

is there a difference between :

cat <<-EOF

and

cat <<EOF  ( without "-" )

regards

[Dennis Handly]

>is there a difference between: cat <<-EOF

As documented, that "-" causes all leading tabs to be removed