Linux Bash while loop reading multiple field text input and running remote commands

bong_water · 02-11-2015, 06:53 PM

I need to create a lot of file systems, of different sizes, owners, groups, and mount points, on a lot of different servers on a regular basis. The file system info was provided to me in a spreadsheet with the following info:

Code:

servername mountpoint owner group size

My script works when I echo the information to the screen. It will go through all 20 or so lines to the end of the file. When it ssh's to the server to run the commands it only runs the first line of the input file and the script exits. What am I missing to make the script go through all of the text file?

Code:

#!/bin/bash
input=fs.txt
 
## Read in Data loop
 
while read -r line
do
  IFS=$'\t' "server" "mount" "owner" "group" "size"<<<"$line"
 
echo "Host : $server" "Mount: $mount" "Owner: $owner" "Group: $group" "Size: $size";
 
 
## Login to server
ssh -xq user@${server} "mkdir -p '$mount'";
ssh -xq user@${server} "chown '$owner':'$group' '$mount'";
 
done < "$input"

Thanks

Keith Hedger · 02-11-2015, 07:48 PM

one of the commands inside the loop is swallowing data from stdin , save stdin just after the do command and restore it just before the done command, sorry not at my machine at moment so can;t give you a code example but have a look at the advanced bash scripting guide

grail · 02-11-2015, 10:28 PM

As with most things, you have several options:

1. Investigate the '-n' option for ssh

2. Use exec to open a file descriptor for your file and the pass read the '-u' option and your fd number

i would add that instead of setting IFS inside the loop and separating your line, you can simply do the same at the read line and use your separate naming convention:

Code:

while IFS=$'\t' read -r server mount owner group size