Echo only valid user - linux

Bash newbie question: I'd like to have this script echo out only users from a given list that are valid user IDs, and not echo the invalid ones.
Here's what I have so far:
#!/bin/bash
while IFS= read -r line
do
id "$line"
if [ $? -eq 1 ] ; then
echo $line
else
echo "$line is not valid user ID" >&2
fi
done < "$1"
Instead, it is echoing out the results of 'id' as well as the text "is not valid user ID"
uid=17931(wwirls) gid=100000(all_usr) groups=100000(all_usr),12(everyone),62(netaccounts),701(1)
wwirls is not valid CruzID
id: smak: no such user
smak
Ideally, it'd echo results like:
wwirls
otheruserid
admin
Your help is appreciated!

id "$line" &> /dev/null
is probably the smallest change that will do what you want. That says to send the output of id (including any error messages) to the bit bucket (/dev/null). However, the sense of your test is backwards - $? is 0 on success, and 1 on failure.
Now, as it happens, if automatically looks at $?. So you can shorten this to:
if id "$line" &> /dev/null # Find out if the user exists, without printing anything
then
echo "$line" # The user exists (`id` succeeded)
else
echo "$line is not valid user ID" >&2 # No such user
fi
Edit 2 If you don't need the not valid output, you can replace the whole if..fi block with
id "$line" &> /dev/null && echo "$line"
If the command before && succeeds, bash runs the command after &&.

Related

Bash script that allows one word as user input

Made a script that the user gives a "parameter" and it prints out if it is a file, directory or non of them. This is it :
#!/bin/bash
read parametros
for filename in *
do
if [ -f "$parametros" ];
then
echo "$parametros is a file"
elif [ -d "$parametros" ];
then
echo "$parametros is a directory"
else
echo " There is not such file or directory"
fi
exit
done
Altough i want the user to be allowed to give only one word as a parameter. How do i make this happen ? (For example if user press space after first word there would be an error message showing "wrong input")
#!/bin/bash
read parametros
if [[ "$parametros" = *[[:space:]]* ]]
then
echo "wrong input"
elif [[ -f "$parametros" ]]
then
echo "$parametros is a file"
elif [[ -d "$parametros" ]]
then
echo "$parametros is a directory"
else
echo " There is not such file or directory"
fi
See http://mywiki.wooledge.org/BashFAQ/031 for the difference between [...] and [[...]].
You have to use the $#. It gives the number of the parameters.
The code will be something like:
if [ "$#" -ne 1 ]; then
printf 'ERROR!\n'
exit 1
fi
First, I'm curious why you want to restrict to one word - a file or directory could have spaces in it, but maybe you are preventing that somehow in your context.
Here are a few ways you could approach it:
Validate the input after they enter it - check if it has any spaces, eg: if [[ "parametros" == *" " ]]; then...
Get one character at a time in a while loop, eg with: read -n1 char
Show an error if it's a space
Break the loop if it's 'enter'
Build up the overall string from the entered characters
1 is obviously much simpler, but maybe 2 is worth the effort for the instant feedback that you are hoping for?

Why doesn't string comparison with wildcards work properly?

I wrote this shell code, but it doesn't get the good output.
Even though the $csoport gets the "...: No such user" output, id doesn't echoes the following line I wrote there.
read felhasznalo
while [ "$felhasznalo" != "exit" ]
do
csoport=`groups $felhasznalo`
echo "$csoport"
if [[ "$csoport" == *": No such user"* ]] ; then
echo -n "Nincs ilyen felhasznalo a rendszerben"
else
echo "$csoport"
fi
echo -n "Felhasznalo: "
read felhasznalo
done
You shouldn't try to match the error messsage since you only care if groups fails. You ought to do:
if ! csoport=$(groups "$felhasznalo"); then
printf "Nincs ilyen felhasznalo a rendszerben"
else
echo "$csoport"
fi

How to read two input values in bash?

I am writing a bash script which takes multiple user inputs. Before the script will take any action, I want to ensure that all values have been added by a user.
#/bin/bash
read -p "Please enter the domain Name: " domain
read -p "Please Enter path where you want to save your result: " path
if [[ -z "$domain" && "$path"]]; then
echo "You have not entered the Domain Name"
exit 1
else
echo "Do Something Here"
fi
I have checked with 1 user input, working fine, but when trying with 2 user inputs, I am getting an error.
./test.sh: line 5: unexpected token `;', conditional binary operator expected
./test.sh: line 5: syntax error near `;'
./test.sh: line 5: `if [[ -z "$domain" && "$path"]]; then'
Thanks!
Because you're using the [[ double brackets, you can use || to test if either of your conditions is true. In this case, your code would look like this:
#!/usr/bin/env bash
read -p "Please enter the domain Name: " domain
read -p "Please Enter path where you want to save your result: " path
if [[ -z "$domain" || -z "$path" ]]; then
echo "Either you have not entered the Domain Name, or you have not entered the path."
exit 1
else
echo "Do Something Here"
fi
Note that spaces around the brackets are necessary.
As others have pointed out, errors should be specific, so you should consider something like this:
if [[ -z "$domain" ]]; then
echo "You have not entered the Domain Name"
exit 1
elif [[ -z "$path" ]]; then
echo "You have not entered the path"
exit 1
fi
echo "Do something here"
It's a bit more verbose but gives the user more specific feedback.
You are getting syntax error because you forgot to put a space between "$path" and ] (bash uses spaces as delimiters).
If you want to fail when at least one condition is wrong, you should use the || (OR) operator.
#/bin/bash
read -p "Please enter the domain name: " domain
read -p "Please enter the path where you want to save your result: " path
if [[ -z "$domain" ]] || [[ -z "$path" ]] ; then
echo "You didn't enter the domain name or the save path"
exit 1
else
echo "Do something here"
fi

Run Linux shell script with arguments

Can somone help me with this: so i have this script
#!/bin/bash
echo -n "Enter a value for X:(999 to exit): "
read x
until [[ $x == 999 ]]
do
echo -n "Enter a value for Y: "
read y
echo "X="$x
echo "Y="$y
((a=y+x))
echo "X+Y="$a
((s=y-x))
echo "X-Y="$s
((m=y*x))
echo "X*Y="$m
((d=y/x))
echo "X/Y="$d
((m=y%x))
echo "X%Y="$m
echo -n "Enter a value for X:(999 to exit): "
read x
if [[ $x == 999 ]];
then
exit 0
fi
done
exit 0
but i didnt know how to write the rest of it, the missing thing is:
Use the two command line arguments when the script starts if the user supplied them, and then prompt for more numbers to continue in the loop.
Am guessing the arguments you are looking from the user are x and y values. The easiest way to check if user provided arguments is to use $# which gets you the number of arguments given by the user.
So use it like this:
if [ "$#" -eq 2 ]; #2 arguments provided by user
then
x=$1
...
fi

Improve Bash script to obtain file names, remove part of their names, and display the result until a key is entered

I have fully working code that obtains a list of file names from the '$testDir', removes the final 3 characters from each, runs a different script using the adjusted names, and displays a list of the edited names that had errors when used in the seperate script, until the letter 'q' is entered by the user.
Here is the code:
#!/bin/bash
# Declarations
declare -a testNames
declare -a errorNames
declare -a errorDescription
declare resultDir='../Results'
declare outputCheck=''
declare userEntry=''
declare -i userSelect
# Obtain list of files in $resultDir and remove the last 3 chars from each file name
for test in `ls $resultDir`; do
testNames+=("${test::-3}")
done
# Run 'checkFile.sh' script for each adjusted file name and add name and result to apporopriate arrays if 'checkFile.sh' script fails
for f in "${testNames[#]}"; do
printf '%s' "$f: "
outputCheck=$(./scripts/checkFile.sh -v "${f}" check)
if [[ $outputCheck != "[0;32mNo errors found.[0m" ]];
then
errorNames+=("$f")
errorDescription+=("$outputCheck")
echo -e '\e[31mError(s) found\e[0m'
else
printf '%s\n' "$outputCheck"
fi
done
#Prompts user to save errors, if any are present
if [ "${#errorNames[#]}" != 0 ];
then
until [[ $userEntry = "q" ]]; do
echo "The following tests had errors:"
for(( i=1; i<=${#errorNames[#]}; i++ )); do
echo -e $i: "\e[31m${errorNames[i-1]}\e[0m"
done
echo "Enter the corresponding number in the list to save the errors found or enter 'q' to quit"
read -r userEntry
numInput=$userEntry
if [ $numInput -gt 0 -a $numInput -le ${#errorNames[#]} ];
then
mkdir -p ./Errors
echo -e "File" "\e[96m${errorNames[$userEntry-1]}""_Error_Info.txt\e[0m created in the 'Errors' folder which contains details of the error(s)"
echo "${errorDescription[$userEntry-1]}" > "./Errors/""${errorNames[$userEntry-1]}""_Error_Info.txt"
fi
done
echo 'Successfully Quit'
exit $?
fi
echo 'No errors found'
exit $?
As someone who is new to Bash and programming concepts, I would really appreciate any suggested improvements to this code. In particular, the script needs to run quickly as the 'checkFile.sh' script takes a long time to run itself. I have a feeling the way I have written the code is not concise either.

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