Here is my code:
#!/bin/bash
echo "Letter:"
read a
if [ $a = "a" ]
then
echo "LOL"
fi
if [ $a = "b" ]
then
echo "ROFL"
fi
Is there a way for me to loop this so that, after displaying either LOL or ROFL, I would be asked for a letter again?
Yes.
Oh, you want to know how?
while true; do
echo "Letter:"
read a
if [ $a = "a" ]
then
echo "LOL"
elif [ $a = "b" ]
then
echo "ROFL"
fi
done
Of course, you probably want some way to get out of that infinite loop. The command to run in that case is break. I would write the whole thing like this:
while read -p Letter: a; do
case "$a" in
a) echo LOL;;
b) echo ROFL;;
q) break;;
esac
done
which lets you exit the loop either by entering 'q' or generating end-of-file (control-D).
Don't forget that you always want -r flag with read.
Also there is a quoting error on that line:
if [ $a = "a" ] # this will fail if a='*'
So here is a bit better version(I've also limited the user to input only 1 character):
#!/bin/bash
while true; do
read -rn1 -p 'Letter: ' a
echo
if [[ $a = 'a' ]]; then
echo "LOL"
elif [[ $a = 'b' ]]; then
echo "ROFL"
else
break
fi
done
Or with switch statement:
#!/bin/bash
while read -rn1 -p 'Letter: ' a; do
echo
case $a in
a) echo LOL;;
b) echo ROFL;;
*) break;;
esac
done
Related
#!/bin/bash
var="true"
i=1
while $var
do
read -p "Enter value (true/false): " var
if [[ $var == "true" ]]
then
echo "Iteration : $i"
((i++))
elif [[ $var == "false" ]]
then
echo "Exiting the process"
elif [[ $? -eq 1 ]]
then
echo "Invalid Choice."
echo "Avaialable Choices are true or false"
exit
fi
done
Script is Working Fine. I Enter true the loop will iterate for false the script stops.
I want the script will continue asking "Enter Value" if any other value instead of true or false will be entered.
This would do the same with a more academic syntax:
i=0
while :; do
printf 'Enter value (true/false): '
read -r var
case $var in
true)
i=$((i + 1))
printf 'Iteration : %d\n' $i
;;
false)
printf 'Exiting the process\n'
break
;;
*)
printf 'Invalid Choice.\nAvaialable Choices are true or false\n'
;;
esac
done
You might find this to be a cleaner solution:
i=0
while true; do
read -p "enter value: " myinput
if [[ $myinput = true ]]; then
echo "iteration $i"
i=$((i+1))
elif [[ $myinput = false ]]; then
echo "exiting"
exit
else
echo "invalid input"
fi;
done;
The issue I see with your current code is that it is unclear which command's exit status $? refers to. Does it refer to the echo in the previous elif block? Or the last condition check? Or something else entirely?
I'm new in bash. I tried that:
#!/bin/bash
i=1
while [[ $var != "false" ]]
do
read -p "Enter value (true/false): " var
if [[ $var == "true" ]]
then
echo "Iteration : $i"
((i++))
elif [[ $var == "false" ]]
then
echo "Exiting the process"
elif [[ $? -eq 1 ]]
then
echo "Invalid Choice."
echo "Avaialable Choices are true or false"
fi
done
I changed while $var with while [[ $var ]] because while works like if. It runs the given command. In there it is $var's value.
And I moved exit to first elif expression's end. So if user type false program will exit.
My background is in SQL but I've been learning Bash to create tools to help non-Linux users find what they need from my Linux system - I am pretty green with Bash, I apologize if this looks a bit dumb.
The goal of the script is to essentially display all directories within the current directory to the user, and allow them to input 1-9 to navigate to lower directories.
My sticking point is that I'm trying to use arrays to define potential filepaths, since in practice new directories will be added over time and it is not practical to edit the script each time a filepath is added.
Here's my prototype so far, currently it navigates into Test1, Test2, or Test3 then echos pwd to prove it is there.
#Global Variables
DIR_MAIN='/home/admin/Testhome'
#Potential Filepaths
#/home/admin/Testhome/Test1/Test1-1/
#/home/admin/Testhome/Test1/Test1-2/
#/home/admin/Testhome/Test2/Test2-1/
#/home/admin/Testhome/Test2/Test2-2/
#/home/admin/Testhome/Test3/Test3-1/
#/home/admin/Testhome/Test3/Test3-2/
#Defining Array for first user input
arr=($(ls $DIR_MAIN))
#System to count total number of directories in filepath, then present to user for numbered selection
cnt=0
for i in ${arr[#]}
do
cnt=$(($cnt+1))
echo "$cnt) $i"
done
read -p "Select a folder from the list: " answer
case $answer in
1)
cd $DIR_MAIN/${arr[0]}
echo "Welcome to $(pwd)"
;;
2)
cd $DIR_MAIN/${arr[1]}
echo "Welcome to $(pwd)"
;;
3)
cd $DIR_MAIN/${arr[2]}
echo "Welcome to $(pwd)"
;;
esac
I've tried the following, but it doesn't like the syntax (to someone experienced I'm sure these case statements look like a grenade went off in vim).
I'm beginning to wonder if the SELECT CASE road I'm going down is appropriate, or if there is an entirely better way.
#User Input Start
echo "What is the secret number?"
while :
do
read STRING1
case $STRING1 in
1)
echo "Enter the number matching the directory you want and I will go there"
echo "1 - ${arr[0]}"
echo "2 - ${arr[1]}"
echo "3 - ${arr[2]}"
read STRING2
case $STRING2 in
1)
cd $DIR_MAIN/${arr[0]}
echo "Welcome to" $(pwd)
2)
cd $DIR_MAIN/${arr[1]}
echo "Welcome to" $(pwd)
3)
cd $DIR_MAIN/${arr[2]}
echo "Welcome to" $(pwd)
*)
echo "Thats not an option and you know it"
*)
echo "1 is the secret number, enter 1 or nothing will happen"
;;
esac
#break needs to be down here somewhere
done
Ultimately I know I'll need to variabilize a local array once I'm in Test2 for example (since in practice, this could descend as far as /Test2/Test2-9 and there would be tons of redundant code to account for this manually).
For now, I'm just looking for the best way to present the /Test2-1 and /Test2-2 filepaths to the user and allow them to make that selection after navigating to /Test2/
This might do what you wanted.
#!/usr/bin/env bash
shopt -s nullglob
n=1
for i in /home/admin/Testhome/Test[0-9]*/*; do
printf '%d) %s\n' "$n" "$i"
array[n]="$i"
((n++))
done
(( ${#array[*]} )) || {
printf 'It looks like there is/are no directory listed!\n' >&2
printf 'Please check if the directories in question exists!\n' >&2
return 1
}
dir_pattern_indices=$(IFS='|'; printf '%s' "#(${!array[*]})")
printf '\n'
read -rp "Select a folder from the list: " answer
if [[ -z $answer ]]; then
printf 'Please select a number and try again!' >&2
exit 1
elif [[ $answer != $dir_pattern_indices ]]; then
printf 'Invalid option %s\n' "$answer" >&2
exit 1
fi
for j in "${!array[#]}"; do
if [[ $answer == "$j" ]]; then
cd "${array[j]}" || exit
printf 'Welcome to %s\n' "$(pwd)"
break
fi
done
The script needs to be sourced e.g.
source ./myscript
because of the cd command. See Why can't I change directory using a script.
Using a function instead of a script.
Let's just name the function list_dir
list_dir() {
shopt -s nullglob
declare -a array
local answer dir_pattern_indices i j n
n=1
for i in /home/admin/Testhome/Test[0-9]*/*; do
printf '%d) %s\n' "$n" "$i"
array[n]="$i"
((n++))
done
(( ${#array[*]} )) || {
printf 'It looks like there is/are no directory listed!\n' >&2
printf 'Please check if the directories in question exists!\n' >&2
return 1
}
dir_pattern_indices=$(IFS='|'; printf '%s' "#(${!array[*]})")
printf '\n'
read -rp "Select a folder from the list: " answer
if [[ -z $answer ]]; then
printf 'Please select a number and try again!' >&2
return 1
elif [[ $answer != $dir_pattern_indices ]]; then
printf 'Invalid option %s\n' "$answer" >&2
return 1
fi
for j in "${!array[#]}"; do
if [[ $answer == "$j" ]]; then
cd "${array[j]}" || return
printf 'Welcome to %s\n' "$(pwd)"
break
fi
done
}
All of the array names and variables are declared local to the function in order not to pollute the interactive/enviromental shell variables.
Put that somewhere in your shellrc file, like say in ~/.bashrc then source it again after you have edited that shellrc file.
source ~/.bashrc
Then just call the function name.
list_dir
I took what #Jetchisel wrote and ran with it - I see they updated their code as well.
Between that code and what I hacked together piggybacking off what he wrote, I'm hoping future viewers will have what they need to solve this problem!
My code includes a generic logging function (can write to a log file if you define it and uncomment those logging lines, for a script this size I just use it to output debugging messages), everything below is the sequence used.
As he mentioned the "0" element needs to be removed from the array for this to behave as expected, as a quick hack I ended up assigning array element 0 as null and adding logic to ignore null.
This will also pull pretty much anything in the filepath, not just directories, so more tweaking may be required for future uses but this serves the role I need it for!
Thank you again #Jetchisel !
#hopt -s nullglob
DIR_MAIN='/home/admin/Testhome'
Dir_Cur="$DIR_MAIN"
LOG_LEVEL=1
array=(NULL $(ls $DIR_MAIN))
########FUNCTION LIST#########
####Generic Logging Function
Log_Message()
{
local logLevel=$1
local logMessage=$2
local logDebug=$3
local dt=$(date "+%Y-%m-%d %T")
##Check log level
if [ "$logLevel" == 5 ]
then local logLabel='INFO'
elif [ "$logLevel" == 1 ]
then local logLabel='DEBUG'
elif [ "$logLevel" == 2 ]
then local logLabel='INFO'
elif [ "$logLevel" == 3 ]
then local logLabel='WARN'
elif [ "$logLevel" == 4 ]
then local logLabel='ERROR'
fi
##Check conf log level
if [ "$LOG_LEVEL" == 1 ]
then #echo "$dt [$logLabel] $logMessage" >> $LOG_FILE ##Log Message
echo "$dt [$logLabel] $logMessage" ##Echo Message to Terminal
##Check if Debug Empty
if [ "$logDebug" != "" ]
then #echo "$dt [DEBUG] $logDebug" >> $LOG_FILE ##Extra Debug Info
echo "$dt [DEBUG] $logDebug" ##Extra Debug Info
fi
elif [ "$logLevel" -ge "$LOG_LEVEL" ]
then #echo "$dt [$logLabel] $logMessage" >> "$LOG_FILE" ##Log Message
echo "$dt [$logLabel] $logMessage"
fi
}
####
####Function_One
##Removes 0 position in array by marking it null, generates [1-X] list with further filepaths
Function_One()
{
Log_Message "1" "entered Function_One"
local local_array=("$#")
Log_Message "1" "${local_array[*]}"
n=1
for i in "${local_array[#]}"; do
if [ "$i" != "NULL" ]
then
printf '%d) %s\n' "$n" "$i"
array[n]="$i"
((n++))
fi
done
printf '\n'
read -rp "Select a folder from the list: " answer
for j in "${!local_array[#]}"; do
if [[ $answer == "$j" ]]; then
cd "$Dir_Cur/${local_array[j]}" || exit
printf 'Welcome to %s\n' "$(pwd)"
break
fi
done
}
####
########FUNCTION LIST END#########
########MAIN SEQUENCE########
echo "Script start"
Function_One "${array[#]}"
Dir_Cur="$(pwd)"
array2=(NULL $(ls $Dir_Cur))
Function_One "${array2[#]}"
Dir_Cur="$(pwd)"
$Dir_Cur/test_success.sh
echo "Script end"
########
Restricting user from trying multiple invalid attempt in shell scripting. I wrote the below script but somehow it's not getting me desire output. I have shared the script and script output both. Kindly help. Here I wanted script to terminate if user tried more than 3 times.
While true
do
echo -n "Enter yes or no"
read opt
case $opt in
yes) break ;;
no) break ;;
*) echo "Invalid input"
while [[ $err -le 3 ]]
do
If [[ $err -le 3 ]]
then
echo "err: $err"
((err++))
break
else
echo "Max limit crossed"
exit 1
fi
done
;;
esac
done
This was a nice question and I had a lot of fun solving it. I have to mention that I'm new to shell programming.
n=0
until [ $n -ge 3 ]
do
read line
if [ "$line" = "XYZ" ]; then
echo "Accepted"
break
else
n=$[$n+1]
echo " trying " $n "times "
fi;
done
This article helped me a lot to solve it.
Try:
#!/bin/bash
ANSWER=
max=3
while true; do
echo "Enter yes or no:"
read -r ANSWER
[[ $ANSWER == "yes" || $ANSWER == "no" ]] && break
echo Invalid Input
ANSWER=
((--max))
[[ $max -le 0 ]] && { echo "Max limit crossed"; exit 1; }
done
Long story short, I need to write a shell script. The script will take a single command line argument which will be a directory path.
The script will then read each of the files in that directory and output it to standard output; the output will be in HTML and will be a table.
The files will be in this format:
owner sysadmin group
admin ajr
loc S-309
ser 18r97
comment noisy fan
What I have so far:
PATH=/bin:/usr/bin
cd "$#"
if [ test $? -ne 0]
then
exit 1
fi
filenames=$(ls "$#")
for i in $filenames
do
while read item value
do
if [ $item="owner" ] || [ $item="admin" ] || [ $item="loc" ] || [ $item="ser"]
then
a[$item]=$value
fi
done < i
done
echo '<html>'
echo '<body>'
echo '<table border=1>'
echo '<tr><th>hostname</th><th>location</th><th>Admin</th><th>Serial Number</th><th>owner</th><tr>'
for i in filename
do
echo '<tr><td>'$i'</td><td>'${i[loc]}'</td><td>${i[admin]}'</td><td>'${i[ser]}'</td><td>'${i[owner]}'</td><tr>'
done
echo
echo '</table>'
echo '</body>'
echo '</html>'
The HTML isn't my main concern since I am just following a format given, with each of the values going in between. However, I am getting an error that I have no idea why:
invrep: line 10: i: no such file or directory
but I am using it in a loop. Why is it giving me this error?
Also to confirm, the directory that I used exists; I'm not sure if that has to do with anything though.
Caveat Lector: the code in the question has been edited. The code I commented on may not be the code you can see.
Not directly the problem (chepner diagnosed that in his comment), but:
cd "$#"
if [ test $? -ne 0]
then
exit 1
fi
has a variety of problems. You don't verify that there's only one argument, and you pass all the arguments that are given to cd, which may just quietly ignore the surplus. The test line should use either [ or test but not both. If you use [, the last argument must be ] so you're missing a space:
if test $? -ne 0
if [ $? -ne 0 ]
However, you could short circuit that paragraph by:
cd "$#" || exit 1
(or you could drop the 1 even, though I'd leave it there).
You might want to consider:
case $# in
1) cd "$1" || exit 1;;
*) echo "Usage: $0 directory" >&2; exit 1;;
esac
This verifies that a single argument was passed and that it names a directory you can cd to.
Your looping code also has problems. The while loop should be redirected from "$i" once you've fixed things up:
filenames=$(ls "$#")
for i in $filenames
do
while read item value
do
if [ $item="owner" ] || [ $item="admin" ] || [ $item="loc" ] || [ $item="ser"]
then
a[$item]=$value
fi
done < $i
# Print HTML here!! Not after this loop
done
Your HTML loop has a lot of problems too — notably using $i as an array instead of $a.
PATH=/bin:/usr/bin
case $# in
1) cd "$1" || exit 1;;
*) echo "Usage: $0 directory" >&2; exit 1;;
esac
echo '<html>'
echo '<body>'
echo '<table border=1>'
echo '<tr><th>hostname</th><th>location</th><th>Admin</th><th>Serial Number</th><th>owner</th><tr>'
filenames=$(ls "$#")
for i in $filenames
do
while read item value
do
if [ $item="owner" ] || [ $item="admin" ] || [ $item="loc" ] || [ $item="ser"]
then
a[$item]=$value
fi
done < $i
echo "<tr><td>$i</td><td>${a[loc]}</td><td>${a[admin]}</td><td>${a[ser]}</td><td>${a[owner]}</td><tr>"
done
echo '</table>'
echo '</body>'
echo '</html>'
And that still doesn't fix the problem with using ls to generate a list of file names. For that, given the rest of the script, lose filenames altogether and use for file in * instead. You then need to quote $i in the I/O redirection, too.
PATH=/bin:/usr/bin
case $# in
1) cd "$1" || exit 1;;
*) echo "Usage: $0 directory" >&2; exit 1;;
esac
echo '<html>'
echo '<body>'
echo '<table border=1>'
echo '<tr><th>hostname</th><th>location</th><th>Admin</th><th>Serial Number</th><th>owner</th><tr>'
for i in *
do
while read item value
do
if [ $item = "owner" ] || [ $item = "admin" ] ||
[ $item = "loc" ] || [ $item="ser"]
then
a[$item]=$value
fi
done < "$i"
echo "<tr><td>$i</td><td>${a[loc]}</td><td>${a[admin]}</td><td>${a[ser]}</td><td>${a[owner]}</td><tr>"
done
echo '</table>'
echo '</body>'
echo '</html>'
(Also fixed spacing in the if statement in the loops. The code is still not very elegant, but it is somewhat related to the original code.)
filenames=$(ls "$#")
is wrong, and should never be used by anyone. See the first entry in http://mywiki.wooledge.org/BashPitfalls, or the entire page http://mywiki.wooledge.org/ParsingLs.
If your argument list is a set of directories, the inner loop would look more like this:
declare -A a
for dir in "$#"; do
for i in "$dir/"*; do
while read -r item value; do
case $item in
owner|admin|loc|ser)
a[$item]=$value
;;
esac
done <"$i"
done
done
I have a test script the needs to read the variable 'LAB' and e-mail the correct company.
I've looked but can't find anything that has worked yet.
Any thoughts?
#!
#
LAB=3
#
if [ "$LAB" = "$1" ];then
echo "Got Zumbrota" && ./mailZ
fi
#
if [ "$LAB" = "$2" ];then
echo "Got Barron" && ./mailB
fi
#
if [ "$LAB" = "$3" ];then
echo "Got Stearns" && ./mailS
fi
If this a bash script, start your file with
#!/bin/bash
and use -eq for integer comparison and since LAB is an integer in your script
if [ $LAB -eq $1 ]
These cascading if statements can be condensed into a case statement:
case "$LAB" in
1) echo "Got Zumbrota" && ./mailZ
;;
2) echo "Got Barron" && ./mailB
;;
3) echo "Got Stearns" && ./mailS
;;
*) echo "don't know what to do with $LAB"
;;
esac