从多个shell命令的输出创建单行

Question

I try to ssh to multiple hosts (thousands of them), capture some command output and write in a file. But output of all command should be in same line, comma separated, space separated, anything but in same line for each host.

So my commands are like":

ssh $host "hostname; uname -r; echo mypassword| sudo -S ipmitool mc info | grep 'Firmware Revision' " > ssh.out

But if I use like this, it will write all command output to separate lines. (3 lines per host). But all I want is only one line per host, let's say:

myserver,3.2.45-0.6.wd.514,4.3 (comma or any field separator is fine)

How I can do this?

Answer 1

It's not very neat but using printf works. hostname and uname -r are verified to work. I don't know what ipmitool outputs so I can't verify it.

ssh $host "printf $(hostname),$(uname -r),$(echo mypassword| sudo -S ipmitool mc info | grep 'Firmware Revision')\n" > ssh.out

Answer 2

You can save the output of ssh into a variable and then print it:

ssh_output=$(ssh $host "hostname; uname -r; echo mypassword | sudo -S ipmitool mc info | grep 'Firmware Revision' ")
printf '%s\n' "$ssh_output"

---

• See this document which explains how shell processes the command output above: Bash Command Substitution
• Related post: How to set a variable to the output from a command in Bash?

Answer 3

Use bash Array variables . Append the output of each ssh command to the array. At the end, echo all elements of the array. The result will be all array elements on a single line. Set IFS (the internal field separator) to desired per-host delimiter. (I used , .) For handling multiple lines of output from multiple commands within the same ssh session, use tr to replace newlines with a delimiter. (I used a space.)

Code

sshoutput=()

for host in host01 host02 host03; do
    sshoutput+=($(ssh $host 'echo $(hostname; uname -a; echo mypassword) | tr "\n" " "'))
done

IFS=,; echo "${sshoutput[*]}";

Output

host01.domain.com Linux host01.domain.com 2.6.32-696.3.1.el6.x86_64 #1 SMP Thu Apr 20 11:30:02 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux mypassword ,host02.domain.com Linux host02.domain.com 2.6.32-696.3.1.el6.x86_64 #1 SMP Thu Apr 20 11:30:02 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux mypassword ,host03.domain.com Linux host03.domain.com 2.6.32-696.3.1.el6.x86_64 #1 SMP Thu Apr 20 11:30:02 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux mypassword