How to format the vaiable output uing printf in a columner way

Question

I have below script which returns the output of the some variables, i am using printf to align the output format but i'm not able to make it correctly formatted either right-justify or left-justify.

Any help will be much appreciated.

Script:

#!/bin/bash
read -rsp $'Please Enter password below: ' SSHPASS
echo -n  ""
export SSHPASS

print "\n"
printf "Hostname        CPU     MEM     SWAP"
remote_connect() {
   target_host=$1
        mem=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" free -g | /bin/awk '/^Mem/{print $2}')
        swap=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" free -g | /bin/awk '/^Swap/{print $2}')
        cpu=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" grep -c proc /proc/cpuinfo)
    printf "%-20s %10s %10s %5s\n" "$target_host" "${cpu} ${mem} ${swap}" 
}  2>/dev/null
export -f remote_connect
< /home/cpls/mb_hosts xargs -P5 -n1 -d'\n' bash -c 'remote_connect "$@"' --

Result:

Hostname        CPU     MEM     SWAP
cpl1855.ind-blr01.cpl.com  4  2  8
cpltp064.ind-blr01.cpl.com  2  1  8
cpltp065.cdi.eu-cdc01.cpl.com  2  1  8
cpl1856.cdi.de-hbg01.cpl.com  2  2  8
cpl1853.cdi.eu-cdc01.cpl.com  2  1  8
cpl1854.cn-sha01.cpl.com  2  1  8
cpl1983.cdi.am-cdc01.cpl.com  2  1  8
cpl1984.cdi.am-cdc01.cpl.com  2  1  8
cpl1986.cdi.am-cdc01.cpl.com  2  1  8

Expected:

There is a utility shipped with RHEL systems called column which is used to columnate lists.

$ cat tt | column -t
Hostname                       CPU  MEM  SWAP
cpl1855.ind-blr01.cpl.com      4    2    8
cpltp064.ind-blr01.cpl.com     2    1    8
cpltp065.cdi.eu-cdc01.cpl.com  2    1    8
cpl1856.cdi.de-hbg01.cpl.com   2    2    8
cpl1853.cdi.eu-cdc01.cpl.com   2    1    8
cpl1854.cn-sha01.cpl.com       2    1    8
cpl1983.cdi.am-cdc01.cpl.com   2    1    8
cpl1984.cdi.am-cdc01.cpl.com   2    1    8
cpl1986.cdi.am-cdc01.cpl.com   2    1    8

Answer 1

read -rsp $'Please Enter password below: ' SSHPASS
echo -n  ""
export SSHPASS

Why do you read the password masked but then export expose it to the whole session environment?

I'd use an ssh key pair with a restricted commands set.

        mem=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" free -g | /bin/awk '/^Mem/{print $2}')
        swap=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" free -g | /bin/awk '/^Swap/{print $2}')
        cpu=$(sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" grep -c proc /proc/cpuinfo)

• If you want to parse the output of free -g, you need to set the locale to C with: LC_ALL=C free -g, or the awk pattern will fail a match on non-US English locale.
• This needlessly establishes 3 distinct ssh sessions to recover data you could get in one go with:

  read -r mem swap cpu < <(
    ssh -o StrictHostKeyChecking=no -q -t "$target_host" \
      awk '/^MemTotal/{printf("%d\t", $2/1000000)};/^SwapTotal/{printf("%d\t", $2/1000000)};/^processor/{c++};END{print c}' /proc/meminfo /proc/cpuinfo
  )

Or even better with only access to cat, download the data and parse locally:

  read -r mem swap cpu < <(
    ssh -o StrictHostKeyChecking=no -q -t "$target_host" \
      cat /proc/meminfo /proc/cpuinfo | 
        awk '/^MemTotal/{printf("%d\t", $2/1000000)};/^SwapTotal/{printf("%d\t", $2/1000000)};/^processor/{c++};END{print c}'
  )

Your snippet fixed:

#!/usr/bin/env bash

read -rsp $'Please Enter password below: ' SSHPASS

export SSHPASS

printf '\n%-32s %10s %10s %5s\n' 'Hostname' 'CPU' 'MEM' 'SWAP'
remote_connect() {
  target_host=$1
  read -r mem swap cpu < <(
    sshpass -e ssh -o StrictHostKeyChecking=no -q -t "$target_host" \
      cat /proc/meminfo /proc/cpuinfo |
      awk '/^MemTotal/{printf("%d\t", $2/1000000)};/^SwapTotal/{printf("%d\t", $2/1000000)};/^processor/{c++};END{print c}'
  )
  printf "%-32s %10s %10s %5s\n" "$target_host" "$cpu" "$mem" "$swap"
} 2>/dev/null
export -f remote_connect

< /home/cpls/mb_hosts xargs -P5 -l1 bash -c 'remote_connect "$1"' --

Example output:

Hostname                                CPU        MEM  SWAP
localhost                                 8         24     6

Answer 2

Your formatting problem (aside from passing the wrong number of arguments originally) is that you are defining less space for your first field than some of its data elements require.

I put the data in a file called data (the formatting isn't about how you acquire the field data).

$: fmt="%-30s %10s %10s %5s\n"
$: printf "$fmt" Hostname        CPU     MEM     SWAP &&
   while read -r -a dat; do printf "$fmt" "${dat[@]}"; done < data
Hostname                              CPU        MEM  SWAP
cpl1855.ind-blr01.cpl.com               4          2     8
cpltp064.ind-blr01.cpl.com              2          1     8
cpltp065.cdi.eu-cdc01.cpl.com           2          1     8
cpl1856.cdi.de-hbg01.cpl.com            2          2     8
cpl1853.cdi.eu-cdc01.cpl.com            2          1     8
cpl1854.cn-sha01.cpl.com                2          1     8
cpl1983.cdi.am-cdc01.cpl.com            2          1     8
cpl1984.cdi.am-cdc01.cpl.com            2          1     8
cpl1986.cdi.am-cdc01.cpl.com            2          1     8

As you obviously already demonstrate, you can set minimum field widths and left-justify with a leading dash (-): -

$: printf "/%-5s/%4s/%3s/%2s/\n" abc def ghi jkl mno pqr stu vwx yz.
/abc  / def/ghi/jkl/
/mno  / pqr/stu/vwx/
/yz.  /    /   /  /

The issue was that if your data is wider than the minimum width the full field is printed (the last field), but otherwise it space-pads (the first two fields).

As an aside, you can add maximum field widths, at the risk of losing info -

$: printf "/%5.5s/%4.4s/%3.3s/%2.2s/\n" abc def ghi jkl mno pqr stu vwx yz.
/  abc/ def/ghi/jk/
/  mno/ pqr/stu/vw/
/  yz./    /   /  /

Note that l and x are lost when the field length truncates them.
That's probably not what you want, though there are times...