I'm new to unix. I have a file with an unknown amount of lines in format: "password, username" and I'm trying to make a function that checks this file against user inputted login.
What I have so far:
Accounts file format:
AAA###, firstname.lastname
echo "Please enter Username:"
read username
if cut -d "," -f2 accounts | grep -w -q $username
then
echo "Success"
fi
This function will return Success for inputs "firstname" "lastname" and "firstname.lastname" when I only want it to return for "firstname.lastname"
Any help would be appreciated.
You could go for an exact match, with ^ and $ anchors, like this:
echo "Please enter Username:"
read username
if cut -d "," -f2 accounts | grep -q "^$username$"; then
echo "Success"
fi
While this would work even when the user gives an empty input, you might want to explicitly check for that.
If you loop over the file within the shell, you can use string equality operators instead of regular expressions:
read -rp "enter Username (first.last): " username
shopt -s extglob
found=false
while IFS=, read -r pass uname _othertext; do
# from your question, it looks like the separator is "comma space"
# so we'll remove leading whitespace from the $uname
if [[ "$username" = "${uname##+([[:blank:]])}" ]]; then
echo "Success"
found=true
break
fi
done < accounts
if ! $found; then
echo "$username not found in accounts file"
fi
while read loops in the shell are very slow compared to grep, but depending on the size of the accounts file you may not notice.
Based on your comment, the issue is that the field separator is a comma then a space, not just a comma. cut can't do multi-character delimiters, but awk can. In your code, replace
cut -d "," -f2
with
awk -F ", " '{print $2}'
By the way, there are a few things needed to guard against user input:
# Use "-r" to avoid backslash escapes.
read -rp "Please enter Username:" username
# Always quote variables ("$username").
# Use "grep -F" for fixed-string mode.
# Use "--" to prevent arguments being interpreted as options.
if awk -F ", " '{print $2}' accounts | grep -wqF -- "$username"; then
echo "Success"
fi
Related
I had problem with cut variables from string in " quotes. I have some scripts to write for my sys classes, I had a problem with a script in which I had to read input from the user in the form of (a="var1", b="var2")
I tried the code below
#!/bin/bash
read input
a=$($input | cut -d '"' -f3)
echo $a
it returns me a error "not found a command" on line 3 I tried to double brackets like
a=$(($input | cut -d '"' -f3)
but it's still wrong.
In a comment the OP gave a working answer (should post it as an answer):
#!/bin/bash
read input
a=$(echo $input | cut -d '"' -f2)
b=$(echo $input | cut -d '"' -f4)
echo sum: $(( a + b))
echo difference: $(( a - b))
This will work for user input that is exactly like a="8", b="5".
Never trust input.
You might want to add the check
if [[ ${input} =~ ^[a-z]+=\"[0-9]+\",\ [a-z]+=\"[0-9]+\"$ ]]; then
echo "Use your code"
else
echo "Incorrect input"
fi
And when you add a check, you might want to execute the input (after replacing the comma with a semicolon).
input='testa="8", testb="5"'
if [[ ${input} =~ ^[a-z]+=\"[0-9]+\",\ [a-z]+=\"[0-9]+\"$ ]];
then
eval $(tr "," ";" <<< ${input})
set | grep -E "^test[ab]="
else
echo no
fi
EDIT:
#PesaThe commented correctly about BASH_REMATCH:
When you use bash and a test on the input you can use
if [[ ${input} =~ ^[a-z]+=\"([0-9]+)\",\ [a-z]+=\"([0-9])+\"$ ]];
then
a="${BASH_REMATCH[1]}"
b="${BASH_REMATCH[2]}"
fi
To extract the digit 1 from a string "var1" you would use a Bash substring replacement most likely:
$ s="var1"
$ echo "${s//[^0-9]/}"
1
Or,
$ a="${s//[^0-9]/}"
$ echo "$a"
1
This works by replacing any non digits in a string with nothing. Which works in your example with a single number field in the string but may not be what you need if you have multiple number fields:
$ s2="1 and a 2 and 3"
$ echo "${s2//[^0-9]/}"
123
In this case, you would use sed or grep awk or a Bash regex to capture the individual number fields and keep them distinct:
$ echo "$s2" | grep -o -E '[[:digit:]]+'
1
2
3
In a shell script I need to assign the output of few values to different varialbes, need help please.
cat file1.txt
uid: user1
cn: User One
employeenumber: 1234567
absJobAction: HIRED
I need to assign the value of each attribute to different variables so that I can call them them in script. For example uid should be assigned to a new variable name current_uid and when $current_uid is called it should give user1 and so forth for all other attributes.
And if the output does not contain any of the attributes then that attribute value should be considered as "NULL". Example if the output does not have absJobAction then the value of $absJobAction should be "NULL"
This is what I did with my array
#!/bin/bash
IFS=$'\n'
array=($(cat /tmp/file1.txt | egrep -i '^uid:|^cn:|^employeenumber|^absJobAction'))
current_uid=`echo ${array[0]} | grep -w uid | awk -F ': ' '{print $2}'`
current_cn=`echo ${array[1]} | grep -w cn | awk -F ': ' '{print $2}'`
current_employeenumber=`echo ${array[2]} | grep -w employeenumber | awk -F ': ' '{print $2}'`
current_absJobAction=`echo ${array[3]} | grep -w absJobAction | awk -F ': ' '{print $2}'`
echo $current_uid
echo $current_cn
echo $current_employeenumber
echo $current_absJobAction
Output from sh /tmp/testscript.sh follows:
user1
User One
1234567
HIRED
#!/usr/bin/env bash
# assuming bash 4.0 or newer: create an associative array
declare -A vars=( )
while IFS= read -r line; do ## See http://mywiki.wooledge.org/BashFAQ/001
if [[ $line = *": "* ]]; then ## skip lines not containing ": "
key=${line%%": "*} ## strip everything after ": " for key
value=${line#*": "} ## strip everything before ": " for value
vars[$key]=$value
else
printf 'Skipping unrecognized line: <%s>\n' "$line" >&2
fi
done <file1.txt # or < <(ldapsearch ...)
# print all variables read, just to demonstrate
declare -p vars >&2
# extract and print a single variable by name
echo "Variable uid has value ${vars[uid]}"
Note that this must be run with bash yourscript, not sh yourscript.
By the way -- if you don't have bash 4.0, you might consider a different approach:
while IFS= read -r line; do
if [[ $line = *": "* ]]; then
key=${line%%": "*}
value=${line#*": "}
printf -v "ldap_$key" %s "$value"
fi
done <file1.txt # or < <(ldapsearch ...)
will create separate variables of the form "$ldap_cn" or "$ldap_uid", as opposed to putting everything in a single associative array.
Here's a simple example of what you are trying to do that should get you started. It assumes 1 set of data in the file. Although a tad brute-force, I believe its easy to understand.
Given a file called file.txt in the current directory with the following contents (absJobAction intentionally left out):
$ cat file1.txt
uid: user1
cn: User One
employeenumber: 1234567
$
This script gets each value into a local variable and prints it out:
# Use /bin/bash to run this script
#!/bin/bash
# Make SOURCEFILE a readonly variable. Make it uppercase to show its a constant. This is the file the LDAP values come from.
typeset -r SOURCEFILE=./file1.txt
# Each line sets a variable using awk.
# -F is the field delimiter. It's a colon and a space.
# Next is the value to look for. ^ matches the start of the line.
# When the above is found, return the second field ($2)
current_uid="$(awk -F': ' '/^uid/ {print $2}' ${SOURCEFILE})"
current_cn="$(awk -F': ' '/^cn/ {print $2}' ${SOURCEFILE})"
current_enbr="$(awk -F': ' '/^employeenumber/ {print $2}' ${SOURCEFILE})"
current_absja="$(awk -F': ' '/^absJobAction/ {print $2}' ${SOURCEFILE})"
# Print the contents of the variables. Note since absJobAction was not in the file,
# it's value is NULL.
echo "uid: ${current_uid}"
echo "cn: ${current_cn}"
echo "EmployeeNumber: ${current_enbr}"
echo "absJobAction: ${current_absja}"
~
When run:
$ ./test.sh
uid: user1
cn: User One
EmployeeNumber: 1234567
absJobAction:
$
I have this script where I ask for 4 patterns and then use those in a grep command. That is, I want to see if a line matches any of the patterns.
echo -n "Enter pattern1"
read pat1
echo -n "Enter pattern2"
read pat2
echo -n "Enter pattern3"
read pat3
echo -n "Enter pattern4"
read pat4
cat somefile.txt | grep $pat1 | grep $pat2 | grep $pat3 | grep $pat4
The problem I'm running into is that if the user doesn't supply one of the patterns (which I want to allow) the grep command doesn't work.
So, is there a way to have grep ignore one of the patterns if it's returned empty?
Your code has lots of problems:
Code duplication
Interactive asking for potentially unused information
using echo -n is not portable
useless use of cat
Here is what I wrote that is closer to what you should use instead:
i=1
printf %s "Enter pattern $i: "
read -r input
while [[ $input ]]; do
pattern+=(-e "$input")
let i++
printf %s "Enter pattern $i (Enter or Ctrl+D to stop entering patterns): "
read -r input
done
echo
grep "${pattern[#]}" somefile.txt
EDIT: This does not answer OP's question, this searches for multiple patterns with OR instead of AND...
Here is a working AND solution (it will stop prompting for patterns on the first empty one or after the 4th one):
pattern=
for i in {1..4}; do
printf %s "Enter pattern $i: "
read -r input
[[ $input ]] || break
pattern="${pattern:+"$pattern && "}/${input//\//\\/}/"
done
echo # skip a line
awk "$pattern" somefile.txt
Here are some links from which you can learn how to program in bash:
Bash Guide
Bash FAQ
I have the following situation:
#!/bin/bash
echo "Please enter a word:"
read foobar
The script is getting called with sh script.sh in the Ubuntu terminal.
Searching on the internet for solutions I found:
foobar=${foobar,,}
echo $foobar
The above approach does only work with bash script.sh
So I went on researching and found:
echo $foobar | tr '[:upper:]' '[:lower:]'
Which does indeed work for both, bash and sh, but without the echo it does not work.
It also prints the read input two times instead of one like so:
Y
y
So how can I do this for sh without printing the read input twice?
It's probably because you didn't assign the translated output to a variable yet. Also I suggest quoting your variables around doublequotes to prevent word splitting and pathname expansion.
foobar=$(echo "$foobar" | tr '[:upper:]' '[:lower:]')
If you're using case and you just need to check if an input is y or Y either way you can use a glob pattern like this. There's no need to transliterate it to lowercase form.
case $foobar in
[yY])
echo "User said yes."
;;
*)
echo "User said no."
;;
esac
Also you can somehow suppress showing user input by using -s:
read -s foobar
As a whole to make your code work well in both bash and sh you should already remove the part which is bash specific:
#!/bin/bash
echo "Please enter a word:"
read -s foobar
foobar=$(echo "$foobar" | tr '[:upper:]' '[:lower:]')
echo "$foobar"
And if it's just about showing the smaller form, you can skip the assignment. But don't use another echo along with it:
#!/bin/bash
echo "Please enter a word:"
read -s foobar
echo "$foobar" | tr '[:upper:]' '[:lower:]'
Another alternative form from case. This is meant to be POSIX compatible.
if [ "$foobar" = y ] || [ "$foobar" = Y ]; then
echo "User said yes."
else
echo "User said no."
fi
In bash it could be simply like this. It would work even in earlier versions that doesn't support ${parameter,,} feature.
if [[ $foobar == [yY] ]]; then
echo "User said yes."
else
echo "User said no."
fi
Use -r option to save the input into REPLY variable and then pipe it to tr command.
read -r -p "Enter something: "; echo "${REPLY}" | tr '[:upper:]' '[:lower:]'
Output:
Enter something: HeLLo, WOrlD!
hello, world!
Do you want to save it in a variable? It's simple, just use command substitution:
foobar=$(read -r -p "Enter something: "; echo "${REPLY}" | tr '[:upper:]' '[:lower:]')
Also, here is another style that is a little simpler (maybe):
read -p "Enter something: " text && tr '[:upper:]' '[:lower:]' <<< "${text}"
Here is a script which reads words from the file replaced.txt and displays the output each word in each line, But I want to display all the outputs in a single line.
#!/bin/sh
echo
echo "Enter the word to be translated"
read a
IFS=" " # Set the field separator
set $a # Breaks the string into $1, $2, ...
for a # a for loop by default loop through $1, $2, ...
do
{
b= grep "$a" replaced.txt | cut -f 2 -d" "
}
done
Content of "replaced.txt" file is given below:
hllo HELLO
m AM
rshbh RISHABH
jn JAIN
hw HOW
ws WAS
ur YOUR
dy DAY
This question can't be appropriate to what I asked, I just need the help to put output of the script in a single line.
Your entire script can be replaced by:
#!/bin/bash
echo
read -r -p "Enter the words to be translated: " a
echo $(printf "%s\n" $a | grep -Ff - replaced.txt | cut -f 2 -d ' ')
No need for a loop.
The echo with an unquoted argument removes embedded newlines and replaces each sequence of multiple spaces and/or tabs with one space.
One hackish-but-simple way to remove trailing newlines from the output of a command is to wrap it in printf %s "$(...) ". That is, you can change this:
b= grep "$a" replaced.txt | cut -f 2 -d" "
to this:
printf %s "$(grep "$a" replaced.txt | cut -f 2 -d" ") "
and add an echo command after the loop completes.
The $(...) notation sets up a "command substitution": the command grep "$a" replaced.txt | cut -f 2 -d" " is run in a subshell, and its output, minus any trailing newlines, is substituted into the argument-list. So, for example, if the command outputs DAY, then the above is equivalent to this:
printf %s "DAY "
(The printf %s ... notation is equivalent to echo -n ... — it outputs a string without adding a trailing newline — except that its behavior is more portably consistent, and it won't misbehave if the string you want to print happens to start with -n or -e or whatnot.)
You can also use
awk 'BEGIN { OFS=": "; ORS=" "; } NF >= 2 { print $2; }'
in a pipe after the cut.