Bash script using awk in for loop

Question

for i in $LIST
do
  CFG=`ssh $i "cat log.txt|awk '{print $2}'"`
  for j in $CFG
  do
    echo $j
  done
done

Say I want to print 2nd field in the log file on a couple remote host. In above script, print $2 doesn't work. How can I fix this? Thanks.

Answer 1

Make sure you're escaping the $2 from the shell - the ssh command you end up sending right now is something like this: ssh listvalue cat log.txt|awk '{print }'

Answer 2

try

for i in $LIST
do
  ssh $i "cat log.txt|awk '{print \$2}'"
done

Answer 3

Lose the cat. Its useless..

for server in $LIST
do
  ssh "$server" "awk '{print \$2}' log.txt"
don

Answer 4

Depending on the number of shell expansions and type of quoting multiple backslash escapes are needed:

awk '{ print $2 }' log.txt # none
ssh $server "awk '{ print \$2 }' log.txt" # one
CFG=`ssh $server "awk '{ print \\$2 }' log.txt"` # two
CFG=$(ssh $server "awk '{ print \$2 }' log.txt") # one (!) 

As a trick you can put a space between the dollar sign and the two to prevent all $ expansion. Awk will still glue it together:

  CFG=`ssh $i "cat log.txt|awk '{print $ 2}'"`

Answer 5

for server in $LIST
do
   ssh "$server" 'awk "{print $2}" log.txt'
done

• Carefully watch the location of the single-quote and the double-quote.
• Bash tries to expand variables (words beginning with $) inside double-quote (").
• Single-quote (') stops Bash from looking for variables inside.
• As user131527 and psj suggested, escaping $2 with \ should also have worked (depending on how your Bash is configured).