Mdthbs

UX writing: When to use "we"?

Applying for mortgage when living together but only one will be on the mortgage

Can birds evolve without trees?

Why are Star Wars Rebel Alliance ships named after letters from the Latin alphabet?

Why do my fried eggs start browning very fast?

Word to describe someone doing something even though told not to

How to power down external drive safely

Does KNN have a loss function?

δόλος = deceit in John 1:47

How did Biff return to 2015 from 1955 without a lightning strike?

Basic theorem proving in Mathematica?

Accurately recalling the key - can everyone do it?

Plotting Chebyshev polynomials using PolarPlot and FilledCurve

Matrix condition number and reordering

Move label of an angle in Tikz

Can I shorten this filter, that finds disk sizes over 100G?

How to get maximum number that newcount can hold?

Why do player start with fighting for the corners in go?

"Will flex for food". What does this phrase mean?

Skipping same old introductions

What's the term for a group of people who enjoy literary works?

What do the screens say after you are set free?

Can I say "Gesundheit" if someone is coughing?

A wiild aanimal, a cardinal direction, or a place by the water

Choose random string from a few and set it as a variable?

Test variable if its string or notIn BASH is there a way to read Variable names from a variable?Local variable as a part of global onempack description (-d) from a script variableCan I introspect the type of a bash variable?How can I use the expanded value of a shell variable in the name of another variable?Makefile: Default Value of Variable that is set but has null valueBash: Set variable equal to a string substitutionHow do I specify chance when setting a variable to random item in array?Evaluate command based on variable at bash

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

0

I have a few strings, and I want to set a variable to one of them, randomly. Say the strings are test001, test002, test003 and test004.

If I set it like normal I'd obviously do it like this:

test=test001

But I want it to choose a random one from the for strings I have. I know I could do something like this, which I have done previously, but that was when choosing a random file from a directory:

test="$(printf "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}")"

But in this case I am not sure how to set testrings.

bash variable

share|improve this question

edited Nov 4 '15 at 14:49

DisplayName

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

bumped to the homepage by Community♦ 36 mins ago

This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  set the teststrings array like this: teststrings=( test001 test002 test003 test004 ), then your code will work. To save running in a subshell, printf -v test "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}"
  
  – glenn jackman
  Nov 4 '15 at 15:01
  
  
  

  
  
  
  

add a comment | 

0

I have a few strings, and I want to set a variable to one of them, randomly. Say the strings are test001, test002, test003 and test004.

If I set it like normal I'd obviously do it like this:

test=test001

But I want it to choose a random one from the for strings I have. I know I could do something like this, which I have done previously, but that was when choosing a random file from a directory:

test="$(printf "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}")"

But in this case I am not sure how to set testrings.

bash variable

share|improve this question

edited Nov 4 '15 at 14:49

DisplayName

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

bumped to the homepage by Community♦ 36 mins ago

This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  set the teststrings array like this: teststrings=( test001 test002 test003 test004 ), then your code will work. To save running in a subshell, printf -v test "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}"
  
  – glenn jackman
  Nov 4 '15 at 15:01
  
  
  

  
  
  
  

add a comment | 

I have a few strings, and I want to set a variable to one of them, randomly. Say the strings are test001, test002, test003 and test004.

If I set it like normal I'd obviously do it like this:

test=test001

But I want it to choose a random one from the for strings I have. I know I could do something like this, which I have done previously, but that was when choosing a random file from a directory:

test="$(printf "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}")"

But in this case I am not sure how to set testrings.

bash variable

share|improve this question

edited Nov 4 '15 at 14:49

DisplayName

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

test=test001

test="$(printf "%sn" "${teststrings[RANDOM % ${#teststrings[@]}]}")"

share|improve this question

edited Nov 4 '15 at 14:49

DisplayName

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

share|improve this question

edited Nov 4 '15 at 14:49

DisplayName

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

asked Nov 4 '15 at 14:34

DisplayNameDisplayName

4,8861212 gold badges4747 silver badges8787 bronze badges

2 Answers
2

active

oldest

votes

0

You can still do something similar:

v=$(printf "test%03d" $(($RANDOM%4+1)))

v=${!v}

where bash ${!variable} does one level of indirection towards the real variable test001 etc.

---

When the names of the variables can be anything, eg test001 somevar anothervar, setup an array:

declare -a teststrings=(test001 somevar anothervar)

v=${teststrings[$(($RANDOM % ${#teststrings[*]}))]}

w=${!v}

echo $w

share|improve this answer

edited Nov 4 '15 at 15:06

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Good answer, but unfortunetaly I might have written my question a bit wrong. The strings can be anything, not just the same thing with increasing numbers. Sorry.
  
  – DisplayName
  Nov 4 '15 at 14:54
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  can you put all the variable names in an array?
  
  – meuh
  Nov 4 '15 at 14:58
  

  
  
  
  

add a comment | 

0

array=(test001 test002 test003 test004)          

totalstr=$((${#array[@]} - 1)) # -1 because 1st string = ${array[0]} , and last one(4th) = ${array[3]

randomnum=$(($(($RANDOM % $totalstr)) + 0)) # get random number between 0 and $totalstr-1

your_random_var=$(echo ${array[$randomnum]})

share|improve this answer

edited Nov 5 '15 at 13:15

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That method to count how many elements the array has will break if any element contains whitespace, or if there are glob-patterns that match files. Simply use totalstr=${#array[@]}.
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You don't need to nest arithmetic expressions: $(( (RANDOM % totalstr) + 0 )) will do, but you don't need to add zero: why do you do that?
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks , I d no idea about the array count, that's why ... !
  
  – Jonah
  Nov 4 '15 at 18:26
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  the '-1' & '+ 0' in both cmds , because the array starts from 0 , ends in totalstr-1 , if not , we won(t be able to call the first string inside the array , and we will call the empty one ${array[4]} as in this example !
  
  – Jonah
  Nov 5 '15 at 13:38
  

  
  
  
  

add a comment | 

Your Answer

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f240751%2fchoose-random-string-from-a-few-and-set-it-as-a-variable%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

0

You can still do something similar:

v=$(printf "test%03d" $(($RANDOM%4+1)))

v=${!v}

where bash ${!variable} does one level of indirection towards the real variable test001 etc.

---

When the names of the variables can be anything, eg test001 somevar anothervar, setup an array:

declare -a teststrings=(test001 somevar anothervar)

v=${teststrings[$(($RANDOM % ${#teststrings[*]}))]}

w=${!v}

echo $w

share|improve this answer

edited Nov 4 '15 at 15:06

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Good answer, but unfortunetaly I might have written my question a bit wrong. The strings can be anything, not just the same thing with increasing numbers. Sorry.
  
  – DisplayName
  Nov 4 '15 at 14:54
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  can you put all the variable names in an array?
  
  – meuh
  Nov 4 '15 at 14:58
  

  
  
  
  

add a comment | 

0

You can still do something similar:

v=$(printf "test%03d" $(($RANDOM%4+1)))

v=${!v}

where bash ${!variable} does one level of indirection towards the real variable test001 etc.

---

When the names of the variables can be anything, eg test001 somevar anothervar, setup an array:

declare -a teststrings=(test001 somevar anothervar)

v=${teststrings[$(($RANDOM % ${#teststrings[*]}))]}

w=${!v}

echo $w

share|improve this answer

edited Nov 4 '15 at 15:06

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Good answer, but unfortunetaly I might have written my question a bit wrong. The strings can be anything, not just the same thing with increasing numbers. Sorry.
  
  – DisplayName
  Nov 4 '15 at 14:54
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  can you put all the variable names in an array?
  
  – meuh
  Nov 4 '15 at 14:58
  

  
  
  
  

add a comment | 

You can still do something similar:

v=$(printf "test%03d" $(($RANDOM%4+1)))

v=${!v}

where bash ${!variable} does one level of indirection towards the real variable test001 etc.

---

When the names of the variables can be anything, eg test001 somevar anothervar, setup an array:

declare -a teststrings=(test001 somevar anothervar)

v=${teststrings[$(($RANDOM % ${#teststrings[*]}))]}

w=${!v}

echo $w

share|improve this answer

edited Nov 4 '15 at 15:06

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

v=$(printf "test%03d" $(($RANDOM%4+1)))

v=${!v}

declare -a teststrings=(test001 somevar anothervar)

v=${teststrings[$(($RANDOM % ${#teststrings[*]}))]}

w=${!v}

echo $w

share|improve this answer

edited Nov 4 '15 at 15:06

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

answered Nov 4 '15 at 14:46

meuhmeuh

33.7k11 gold badge2525 silver badges5959 bronze badges

0

array=(test001 test002 test003 test004)          

totalstr=$((${#array[@]} - 1)) # -1 because 1st string = ${array[0]} , and last one(4th) = ${array[3]

randomnum=$(($(($RANDOM % $totalstr)) + 0)) # get random number between 0 and $totalstr-1

your_random_var=$(echo ${array[$randomnum]})

share|improve this answer

edited Nov 5 '15 at 13:15

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That method to count how many elements the array has will break if any element contains whitespace, or if there are glob-patterns that match files. Simply use totalstr=${#array[@]}.
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You don't need to nest arithmetic expressions: $(( (RANDOM % totalstr) + 0 )) will do, but you don't need to add zero: why do you do that?
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks , I d no idea about the array count, that's why ... !
  
  – Jonah
  Nov 4 '15 at 18:26
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  the '-1' & '+ 0' in both cmds , because the array starts from 0 , ends in totalstr-1 , if not , we won(t be able to call the first string inside the array , and we will call the empty one ${array[4]} as in this example !
  
  – Jonah
  Nov 5 '15 at 13:38
  

  
  
  
  

add a comment | 

0

array=(test001 test002 test003 test004)          

totalstr=$((${#array[@]} - 1)) # -1 because 1st string = ${array[0]} , and last one(4th) = ${array[3]

randomnum=$(($(($RANDOM % $totalstr)) + 0)) # get random number between 0 and $totalstr-1

your_random_var=$(echo ${array[$randomnum]})

share|improve this answer

edited Nov 5 '15 at 13:15

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  That method to count how many elements the array has will break if any element contains whitespace, or if there are glob-patterns that match files. Simply use totalstr=${#array[@]}.
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You don't need to nest arithmetic expressions: $(( (RANDOM % totalstr) + 0 )) will do, but you don't need to add zero: why do you do that?
  
  – glenn jackman
  Nov 4 '15 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks , I d no idea about the array count, that's why ... !
  
  – Jonah
  Nov 4 '15 at 18:26
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  the '-1' & '+ 0' in both cmds , because the array starts from 0 , ends in totalstr-1 , if not , we won(t be able to call the first string inside the array , and we will call the empty one ${array[4]} as in this example !
  
  – Jonah
  Nov 5 '15 at 13:38
  

  
  
  
  

add a comment | 

array=(test001 test002 test003 test004)          

totalstr=$((${#array[@]} - 1)) # -1 because 1st string = ${array[0]} , and last one(4th) = ${array[3]

randomnum=$(($(($RANDOM % $totalstr)) + 0)) # get random number between 0 and $totalstr-1

your_random_var=$(echo ${array[$randomnum]})

share|improve this answer

edited Nov 5 '15 at 13:15

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

array=(test001 test002 test003 test004)          

totalstr=$((${#array[@]} - 1)) # -1 because 1st string = ${array[0]} , and last one(4th) = ${array[3]

randomnum=$(($(($RANDOM % $totalstr)) + 0)) # get random number between 0 and $totalstr-1

your_random_var=$(echo ${array[$randomnum]})

share|improve this answer

edited Nov 5 '15 at 13:15

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges

answered Nov 4 '15 at 15:08

JonahJonah

90366 silver badges1717 bronze badges