I want to make a simple bash script that makes a for loop over a file with commands and execute those commands, and finishes when an error happens. I have something like this
#!/bin/bash
while IFS= read -r line; do
echo $line
output=$(eval $line)
if [ $? -eq 0 ]
then
echo ok
else
echo $output
break
fi
echo
done < summary.txt
The problem is that the first command I'm trying to make is a sudo command, so I have to put the password. I tried putting it in the command like
sudo -S <<< password <<< Y command
with no luck. I've checked that works if I just put it directly without having to read it (not putting it as a string). The thing is that without the loop, the program would be long with no much sense.
Thanks
echo <password> | sudo -S < your command>
From man sudo
-S, --stdin
Write the prompt to the standard error and read the password from the standard input instead of using the terminal
device. The password must be followed by a newline character.
Related
I'm trying to run this command over multiple machines
sshpass -p 'nico' ssh -o 'StrictHostKeyChecking=no' nico#x.x.x.x "mkdir test"
The IPs are stored in the following .txt file
$ cat ips.txt
10.0.2.15
10.0.2.5
I created a bash script that reads this file line by line. If I run it with an echo:
#!/bin/bash
input="ips.txt"
while IFS= read -r line
do
echo "$line"
#sshpass -p 'nico' ssh -o 'StrictHostKeyChecking=no' nico#$line "mkdir test"
done < "$input"
It prints every line:
$ ./variables.sh
10.0.2.15
10.0.2.5
This makes me understand that the script is working as intended. However, when I replace the echo line with the command I want to run for each line:
#!/bin/bash
input="ips.txt"
while IFS= read -r line
do
#echo "$line"
sshpass -p 'nico' ssh -o 'StrictHostKeyChecking=no' nico#$line "mkdir test"
done < "$input"
It only performs the action for the first IP on the file, then stops. Why?
Managed to solve this by using a for instead of a while. Script ended up looking like this:
for file in $(cat ips.txt)
do
sshpass -p 'nico' ssh -o 'StrictHostKeyChecking=no' nico#$file "mkdir test"
done
While your example is a solution that works, it's not the explanation.
Your could find the explanation here : ssh breaks out of while-loop in bash
In two words :
"while" loop continue reading from the same file-descriptor that defined in the loop header ( $input in your case )
ssh (or sshpass) read data from stdin (but in your case from file descriptor $input). And here is the point that hide the things as we didn't exect "ssh" to read the data.
Just to understand the problem you could have same strange experience for example using commands like "ffmpeg" or "mplayer" in while loop. Mplayer and ffmpeg use the keyboards while they are running, so they will consume all the the file-descriptor.
Another good and funny example :
#!/bin/bash
{
echo first
for ((i=0; i < 16384; i++)); do echo "testing"; done
echo "second"
} > test_file
while IFS= read -r line
do
echo "Read $line"
cat | uptime > /dev/null
done < test_file
At first part we write 1st line : first
16384 lines : testing
then last line : second
16384 lines "testing" are equal to 128Kb buffer
At the second part, the command "cat | uptime" will consume exactly 128Kb buffer, so our script will give
Read first
Read second
As solution, as you did, we could use "for" loop.
Or use "ssh -n"
Or playing with some file descriptor - you could find the example in the link that I gave.
I'm trying to run a task where I have a script that will add a user to a remote server via ssh.
Here is my code:
#echo off
setlocal enabledelayedexpansion
set username=%1
set password=%2
for /F "tokens=*" %%a in (Linuxhosts.txt) do (
ssh -i svcaccount_id_rsa svcaccount#%%a 'bash -s' < adduser.txt
)
Here are the contents of the adduser.txt file
#!/bin/bash
#========================================================================================================
# This script allows for account creation on a server |
# It also performs error handling to ensure that the user doesn't currently exist on the system. |
# Also provides feedback from the input to verify the entries are correct. |
#========================================================================================================
while true; do
echo -n "Enter username: "
read -r username
/bin/egrep -i "^${username}:" /etc/passwd
if [ $? -eq 0 ]; then
echo "User $username already exists. Please check the username and try again."
else
echo "User $username does not exist. Proceed with account creation."
break
fi
done
adduser "$username"
if [ $? -gt 0 ]; then
echo "Error encountered."
exit 1
fi
echo -n "Enter password: "
read -r -s password
echo "$username:$password" | chpasswd
echo "Password was succesfully set for $username."
if [ $? -gt 0 ]; then
echo "Error encountered. There was a problem with your entry. Please re-run the script and try again."
exit 1
fi
usermod -a -G wheel "$username"
echo "User was succesfully added to the group wheel."
if [ $? -gt 0 ]; then
echo "Error encountered."
exit 1
fi
echo "Successfully added $username to the system."
However, when I try to run the first set of code through a cmd prompt, I get the following error:
bash: line 41: syntax error: unexpected end of file
I'm not sure what I'm missing. I have tested it with another file called hello.txt and it ran fine so I'm wondering if maybe there's spacing issues somewhere that I can't see because it's a text file.
I'm pretty sure the immediate problem here is that the file adduser.txt is in DOS/Windows format, with its lines terminated with a carriage return character, followed by a linefeed. Unix (including bash) expects just a linefeed as the line terminator, and hence treats the carriage return as part of the line's text. In this case, that means that bash sees line 17, "done", as "done[carriage return]" which isn't a valid keyword and does not end the while loop, so it keeps looking for the "done" keyword... until it runs out of file.
(Credit to Squashman for suggesting this in a comment.)
You're likely to have this problem a lot transferring files from Windows to unix; unfortunately, the tools available to fix the problem vary quite a bit depending on what OS you're using, etc.
BTW, I see a couple of other problems here. For one thing, the read commands in the script are going to be trying to read from the same source that bash is reading commands from, which is the adduser.txt file. So when it does e.g. read -r username it's actually going to be reading some later line from the script file, not from the user running the batch script. This is going to be very hard to solve the way you're doing it; I think it'll be much better to actually copy the script file to the unix system, then run it separately.
Also, as Socowi pointed out in the comments, $? gets the exit status of the last command executed, so in sections like this:
echo "$username:$password" | chpasswd
echo "Password was succesfully set for $username."
if [ $? -gt 0 ]; then
...
the if condition is checks the exit status of the command echo "Password was succesfully set for $username.", not the chpasswd command. The same problem applies to the usermod command later. The better way to do this is to use the command you want to check for success directly as the if condition:
if echo "$username:$password" | chpasswd; then
echo "Password was succesfully set for $username."
else
echo "Error encountered. There was a problem with your entry. Please re-run the script and try again."
exit 1
fi
I'd use this same format in all of the places you're checking exit status: the egrep, useradd, chpasswd, and usermod commands.
[UPDATE] After a bit of mulling, I have a couple of possible solutions: First, to fix the carriage return problem, you could pipe the file through tr -d "\r" as a quick-n-dirty CR remover (although you may have to play around with the quoting and/or escaping to get that \r through both batch and bash's command processing). Second, pass the username and password as arguments to the script instead of having it read them. Thus, your batch script would use something like this:
ssh -i svcaccount_id_rsa svcaccount#%%a 'tr -d "\r" | bash -s "username" "password"' < adduser.txt
... then change adduser.txt to use username="$1"; password="$2" instead of the read commands (and also changing that while loop into an if, since there wouldn't be an option to try again with a different username).
This bash script when run on Mac terminal, it needs to ask for user input, then it needs to check if a a string "PLACEHOLDER_BACKEND_NAME="user-input" exists in a given file and if not it should exit the script.
echo -e "${YELLOW}enter app name${WHITE}"
read name
line=grep $name /path/to/file/entrypoint.sh
if [[ line != "PLACEHOLDER_BACKEND_NAME=\"$name\"" ]] ; then
exit 1
fi
It needs much tuning as I am not very familiar with bash scripts. any suggestions? thx
Your code needs a little tweaking:
echo -e "${YELLOW}enter app name${WHITE}"
read -r name
if ! grep -q PLACEHOLDER_BACKEND_NAME="\"$name\"" /path/to/file/entrypoint.sh; then
exit 1
fi
I need to read the variable from a remote file over SSH and compare it. But I get a variable in the wrong format. how to do it correctly?
#!/bin/bash
pass='dpassspass'
user='root#10.10.19.18'
IP="10.2.1.41"
path=/sys/variable/serv
#not work## No such file or directory# write=$(sshpass -p $ovhpass ssh -t $user echo "$IP" > $path)
sshpass -p $pass ssh -t $user << EOF
echo "$IP" > $path
EOF
my_var=$(sshpass -p $pass ssh -t $user "cd /sys_ovh; ./serv.bash")
echo mystart-"$my_var"-myend
read=$(sshpass -p $pass ssh -t $user cat $path)
echo start-"$read"-end
echo start-"$IP"-end
if [ "$read" == "$IP" ]; then
echo "run"
fi
output:
Connection to 10.10.19.18 closed.
-myendt-10.2.1.41
Connection to 10.10.19.18 closed.
-endt-10.2.1.41
start-10.2.1.41-end
Where I make a mistake? How to take data from the SSH?
The vars my_var and read are filled with a string ending with '\r', telling echo to go back to the first column. I think this is a problem with your local script. You can correct that with
tr -d "\r" < myfile > myfile2
Your fundamental problem comes from using unquoted here documents for the commands. You should properly understand in which order the shell interprets these contructs.
ssh remote cmd >file
executes cmd remotely, but first redirects the output from the ssh command to the local file.
ssh remote "cmd >’$file'"
The quotes cause the redirection to be part of the remote command line. The variable file is interpreted first, by the local shell, though.
ssh remote 'cmd >"$file"`
The single quotes prevent the local shell from modifying the command before sending it. Thus, he variable interpolation and the redirection are both handled by the remote shell, in this order.
So your commented-out "not work" command could easily be fixed with proper quoting. However, it will be much more elegant and efficient to use a single remote session, and execute all the commands in one go. Mixing the local variable IP with remote variables calls for some rather elaborate escaping, though. A major simplification would be to pass the value on standard input, so that the entire remote script can be single quoted.
#!/bin/bash
pass='dpassspass'
user='root#10.10.19.18'
IP="10.2.1.41"
result=$(echo "$IP" |
sshpass -p "$pass" ssh -t "$user" '
path=/sys/variable/serv
cat > "$path"
cd /sys_ovh
./serv.bash
cat "$path"')
echo mystart-"${result%$'\n'*}"-myend
echo start-"${result#*$'\n'}"-end
echo start-"$IP"-end
if [ "${result#*$'\n'}" == "$IP" ]; then
echo "run"
fi
The output from the remote shell is two lines; we pick it apart by using the shell's prefix and suffix substitution operators.
I have this shell script which ssh to other server, find few specific files(.seq files older than 50 mnts) and writes their name to another file.
#! /usr/bin/bash
while read line
do
#echo $line
if [[ $line =~ ^# ]];
then
#echo $line;
continue;
else
serverIP=`echo $line|cut -d',' -f1`
userID=`echo $line|cut -d',' -f2`
fi
done < sftp.conf
sshpass -p red32hat ssh $userID#$serverIP
cd ./perl
for files in `find -name "*.seq" -mmin +50`
do
#sshpass -p red32hat scp *.seq root#rinacac-test:/root/perl
echo $files>>abcde.txt
done
exit;
#EOF
Now problem is that when I run it.. neither it writes to abcde.txt file nor it is exiting from the remote server. when I manually execute the exit command...it exists saying "perl no such file or directory"... while I have perl sub directory in my home directory..
other thing is when I run the for loop portion of the script on the 2nd server(by directly logging into it) it is working fine and writing to abcde.txt filr...please help...
ssh takes commands either on standard input or as the last parameter. You can therefore do this (very dynamic but tricky to get the expansions right):
ssh user#host <<EOF
some
custom
commands
EOF
or this (less dynamic but can take simple parameters without escaping):
scp my_script.sh user#host:
ssh user#host './my_script.sh'