I'm trying to interpret this block of code. Searched google to see what these commands mean and no luck. I put my interpretation of what each line/block means to me. If I am wrong, please correct me. I am new to unix commands. Code:
#!/bin/bash
# input 1st command line argument for the version.
export VERSION=$1
# if user didn't input a version, print the echo message and exit (not sure what -n means but I am assuming)
if [[ ! -n "$VERSION" ]]; then
echo "Missing Version"
exit 1
fi
# creating variable UNAME that tells who the person is (their name)
export UNAME='whoami'
# no idea what -s and -p mean but i think this prints the message "enter password for $UNAME" and stores it in a new variable named PASSWORD. the $UNAME will print whatever whoami said.
read -s -p "Enter password for $UNAME: " PASSWORD
echo ""
The -p flag issues a prompt before reading input into a variable
The -s flag stop the typed response from being shown (i.e. for a sensitive password)
More information is available here:
https://linuxhint.com/bash_read_command/
-p
prompt output the string PROMPT without a trailing newline before
attempting to read.
-s
do not echo input coming from a terminal.
Related
I am using below code to ssh to different nodes and find if an user exists or not. If the user doesn't exist it will create it.
The script works fine if I don't do ssh but it fails if I do ssh.
How can I go through different nodes using this script?
for node in `nodes.txt`
usr=root
ssh $usr#$node
do
if [ $(id -u) -eq 0 ]; then
read -p "Enter username : " username
read -s -p "Enter password : " password
egrep "^$username" /etc/passwd >/dev/null
if [ $? -eq 0 ]; then
echo "$username exists!"
exit 1
else
pass=$(perl -e 'print crypt($ARGV[0], "password")' $password)
useradd -m -p $pass $username
[ $? -eq 0 ] && echo "User has been added to system!" || echo "F
ailed to add a user!"
fi
else
echo "Only root may add a user to the system"
exit 2
fi
done
Your script has grave syntax errors. I guess the for loop at the beginning is what you attempted to add but you totally broke the script in the process.
The syntax for looping over lines in a file is
while read -r line; do
.... # loop over "$line"
done <nodes.txt
(or marginally for line in $(cat nodes.txt); do ... but this has multiple issues; see http://mywiki.wooledge.org/DontReadLinesWithFor for details).
If the intent is to actually run the remainder of the script in the ssh you need to pass it to the ssh command. Something like this:
while read -r node; do
read -p "Enter user name: " username
read -p -s "Enter password: "
ssh root#"$node" "
# Note addition of -q option and trailing :
egrep -q '^$username:' /etc/passwd ||
useradd -m -p \"\$(perl -e 'print crypt(\$ARGV[0], \"password\")' \"$password\")" '$username'" </dev/null
done <nodes.txt
Granted, the command you pass to ssh can be arbitrarily complex, but you will want to avoid doing interactive I/O inside a root-privileged remote script, and generally make sure the remote command is as quiet and robust as possible.
The anti-pattern command; if [ $? -eq 0 ]; then ... is clumsy but very common. The purpose of if is to run a command and examine its result code, so this is better and more idiomatically written if command; then ... (which can be even more succinctly written command && ... or ! command || ... if you only need the then or the else part, respectively, of the full long-hand if/then/else structure).
Maybe you should only do the remote tasks via ssh. All the rest runs local.
ssh $user#$node egrep "^$username" /etc/passwd >/dev/null
and
ssh $user#$node useradd -m -p $pass $username
It might also be better to ask for username and password outside of the loop if you want to create the same user on all nodes.
I am working on a script which prompts the user for their username. Once entered, the script uses the 'rwho' command to get a list of users who are logged into the network. It should crosscheck the text they entered (their username) with the results from the rwho command.
If a match is found then it displays a message saying so, if not then it also makes the user aware of this.
Here is the script and my attempt so far:
#!/bin/sh
#
# User network checking script
#
# Using rwho command to get user list
OUTPUT="$(rwho)"
echo "${OUTPUT}"
# Prompt for username
echo "Please enter your username: "
read username
# Input validation
if [ -z "$username"]
then
echo "No username supplied"
echo "Please enter your username: "
read username
fi
# Search for user
if `echo ${OUTPUT} | grep "${username}" 1>/dev/null 2>&1'
then
echo "$username is logged in."
else
echo "$username is not present."
fi
I consistently get errors with the Search for User part. I don't have outstanding knowledge of Linux so if anyone could fix this and help me I would be greatly appreciative.
Your usage of quotes is weird.
if echo "$OUTPUT" | grep -q "$username"
should work.
-q makes grep quiet (and is shorter than your redirections).
So I would like to make a script that create users from users.txt running
useradd -m -s /bin/false users_in_the_users.txt
and fill the password from passwords.txt twice (to confirm the passwords)
This is the script
#!/bin/bash
# Assign file descriptors to users and passwords files
exec 3< users.txt
exec 4< passwords.txt
exec 5< passwords.txt
# Read user and password
while read iuser <&3 && read ipasswd <&4 ; do
# Just print this for debugging
printf "\tCreating user: %s with password: %s\n" $iuser $ipasswd
# Create the user with adduser (you can add whichever option you like)
useradd -m -s /bin/false $iuser
# Assign the password to the user, passwd must read it from stdin
passwd $iuser
done
The problem is, it does not fill the passwords. And 1 more thing, I want the script to fill the passwords twice.
Any suggestions?
You have to supply the password on stdin. Replace:
passwd $iuser
with:
passwd "$iuser" <<<"$ipasswd
$ipasswd"
or, as suggested by mklement0:
passwd "$iuser" <<<"$ipasswd"$'\n'"$ipasswd"
The incantation <<< creates a here-string. The string that follows the <<< is provided as standard in to the command which precedes the <<<. In this case we provide the two copies of the password that the passwd command wants.
(The script reads these passwords from a plain text file. I will assume that your situation is some special case for which this is not as dangerous as it normally would be.)
John1024's answer is the correct one - his warning about reading passwords from plain-text files bears repeating.
Let me show the solution in context, without the file-descriptor acrobatics (exec 3<, ...):
#!/bin/bash
# NOTE: Be sure to run this script with `sudo`.
# Read user and password
while read iuser ipasswd; do
# Just print this for debugging.
printf "\tCreating user: %s with password: %s\n" $iuser $ipasswd
# Create the user with adduser (you can add whichever option you like).
useradd -m -s /bin/false $iuser
# Assign the password to the user.
# Password is passed via stdin, *twice* (for confirmation).
passwd $iuser <<< "$ipasswd"$'\n'"$ipasswd"
done < <(paste users.txt passwords.txt)
paste users.txt passwords.txt reads corresponding lines from the two files and puts them on a single line, separated with \t.
The result is piped to stdin via a process substitution (<(...)).
This allows read to read from a single source.
$\n is an ANSI C-quoted string that produces a (literal) newline.
#! /bin/bash
for i in {1..100}
do
`sudo mkdir -p /root/Desktop/userm$i`
`sudo useradd -m -d /root/Desktop/userm$i -s /bin/bash userm$i`
echo "userm$i:userm$i" | chpasswd
done
this will create 100 users. user name will be (userm1-userm100). home directory will be /root/Desktop/(userm1-user100)
password will be (userm1-userm100)
Instead of using this line:
useradd -m -s /bin/false $iuser
Try this one:
useradd -m -s /bin/false -p $ipasswd $iuser
You don't actually need this:
passwd $iuser <<< "$ipasswd"$'\n'"$ipasswd"
Kindly run the below script.
#!/bin/bash
#purpose: bash script to create multiple users with pre-defined passwords at once.
#Read_Me: The import file should be in two columns, first users name and second passwords.
#author: Bablish Jaiswal
#contact: linux.cnf#gmail.com
read -p "Kindly import/type Users Name-password file with location:- " creation_info
cat $creation_info |while read i p
do
( useradd $i && echo -e "${p}\n${p}" | passwd $i ) > /dev/null 2>&1 && echo $user ${i} created and password is ${p} || echo ${i} failed
done
I wrote this sh script here. What it suppose to be doing is it prompts the user to type in the old password, then checks the password with the password in the "PASSWORD.txt" file if not it would exit, else if it matches then it would ask the user to type in the new password twice. Then it checks if the two new passwords are the same if not it would exit, else i should put the input the user typed and replace the text in the "PASSWORD.txt" file.
Then when i ran the file where it askes me for the old password i got this error:
Please Enter teh old passsword:
test
cat: .txt: No such file or directory
The password doesn't match![root#guzzy ~]#
The thing is the input i typed doesn't match even though i typed the correct old password.
Here is the scirpt below:
#!/bin/sh
clear
echo -e "Please Enter the old password:"
read old
if [ "$old" != "$(cat $PASSWORD.txt)" ]
then
echo -n "The password doesn't match!"
exit
else
echo -n "The old password matches!"
echo -n "Please Enter New password:"
read new1
echo -n "Please Enter New password again:"
read new2
if [ "$new1" != "$new2" ]
then
echo -n "The new passwords don't match!"
exit
else
$new1 >> PASSWORD.txt
echo -n "The new password has been saved!"
fi
fi
Please help thanks!
This line:
$new1 >> PASSWORD.txt
should be like this:
echo "$new1" > PASSWORD.txt
You need to echo the value into the file. I'm assuming that you don't want to keep old values. In order to be able to run your script again on the same file, you should probably overwrite (>) rather than append (>>).
You haven't set the PASSWORD variable somewhere. If your file is named 'PASSWORD.txt', remove the $ before it.
It think you meant
if [ "$old" != "$(cat PASSWORD.txt)" ]
without the dollar sign.
I'm trying to write a sh coding to get the user to authenticate the password by comparing the user input to the first 32 characters of a file. So basically if the password is correct it would run TaskMenu.csh if its wrong the program would exit.
#!/bin/sh
clear
echo -e " Please Enter the Password to access the TaskMenu:"
read PW
if (! -e "$PASSWORD.txt")
then
echo -n "The file doesn't exist"
echo kil
exit
else
...(i have no clue what to do)...
Please help
if [ "$PW" = $(cat "$PASSWORD.txt | head -c 32) ]
then
./TaskMenu.csh
else
echo Authentication failed.
exit 3
fi
Run with bash -x, or add set -x to the top of your source to see what strings are being passed around.