Create Multiple Files at Once Using Brace Expansion in BASH

Last Updated on: August 9, 2020

Chances are you’ve come across expansions in BASH, whenever you are going back to the user home directory, we use the cd command alongside a tilde character (~), e.g:

This would take you back to your home directory, and that is because the tilde character represents the value of the user’s home variable, this is called the tilde expansion.

Another type of expansion that we are concerned about in this guide is the brace expansion, this is a handy command that can save you a ton with repeated commands when working with a range of terms.

For example, to create a multiple files with the touch command using the brace expansion, we do:

Note: Create a temporary directory for this example: mkdir cat

					

touch {persian,maine,siamese,bengal}

This would create the four file all in one go, you see how handy that is, you don’t have to keep repeating the command one after the order.

Yeah, this is cool but what if you want to create hundreds or thousands of files at once, then we can use interpolation, this is creating files from know name in a given range.

To create a file_1 – file_100, we do:

This would create a 100 of new files, you can in fact create a thousand of file with this method. If you try listing the files created with this command, you would see that they aren’t properly sorted, for example, here is the output of the one I just created:

					

user@server:~/cat$ ls
file_1    file_17  file_25  file_33  file_41  file_5   file_58  file_66  file_74  file_82  file_90  file_99
file_10   file_18  file_26  file_34  file_42  file_50  file_59  file_67  file_75  file_83  file_91
file_100  file_19  file_27  file_35  file_43  file_51  file_6   file_68  file_76  file_84  file_92
file_11   file_2   file_28  file_36  file_44  file_52  file_60  file_69  file_77  file_85  file_93
file_12   file_20  file_29  file_37  file_45  file_53  file_61  file_7   file_78  file_86  file_94
file_13   file_21  file_3   file_38  file_46  file_54  file_62  file_70  file_79  file_87  file_95
file_14   file_22  file_30  file_39  file_47  file_55  file_63  file_71  file_8   file_88  file_96
file_15   file_23  file_31  file_4   file_48  file_56  file_64  file_72  file_80  file_89  file_97
file_16   file_24  file_32  file_40  file_49  file_57  file_65  file_73  file_81  file_9   file_98
user@server:~/cat$

This is really disorganized, which isn’t something I would want. To correct this we can use zero padding, if you are testing this in a test directory remove the ones we have created before with rm *

Now, to pad it, we simply use one zero:

Even if you are padding thousands of files, one zero is all it takes, here is the output of the above command:

					

ls
file_001  file_011  file_021  file_031  file_041  file_051  file_061  file_071  file_081  file_091
file_002  file_012  file_022  file_032  file_042  file_052  file_062  file_072  file_082  file_092
file_003  file_013  file_023  file_033  file_043  file_053  file_063  file_073  file_083  file_093
file_004  file_014  file_024  file_034  file_044  file_054  file_064  file_074  file_084  file_094
file_005  file_015  file_025  file_035  file_045  file_055  file_065  file_075  file_085  file_095
file_006  file_016  file_026  file_036  file_046  file_056  file_066  file_076  file_086  file_096
file_007  file_017  file_027  file_037  file_047  file_057  file_067  file_077  file_087  file_097
file_008  file_018  file_028  file_038  file_048  file_058  file_068  file_078  file_088  file_098
file_009  file_019  file_029  file_039  file_049  file_059  file_069  file_079  file_089  file_099
file_010  file_020  file_030  file_040  file_050  file_060  file_070  file_080  file_090  file_100

You see how organized this is. You don’t have to stop, you can also create a specific file extension in one go, to create hundreds of txt files at once, we do:

					

touch book{01..100}.txt
ls
ls
book001.txt  book014.txt  book027.txt  book040.txt  book053.txt  book066.txt  book079.txt  book092.txt
book002.txt  book015.txt  book028.txt  book041.txt  book054.txt  book067.txt  book080.txt  book093.txt
book003.txt  book016.txt  book029.txt  book042.txt  book055.txt  book068.txt  book081.txt  book094.txt
book004.txt  book017.txt  book030.txt  book043.txt  book056.txt  book069.txt  book082.txt  book095.txt
book005.txt  book018.txt  book031.txt  book044.txt  book057.txt  book070.txt  book083.txt  book096.txt
book006.txt  book019.txt  book032.txt  book045.txt  book058.txt  book071.txt  book084.txt  book097.txt
book007.txt  book020.txt  book033.txt  book046.txt  book059.txt  book072.txt  book085.txt  book098.txt
book008.txt  book021.txt  book034.txt  book047.txt  book060.txt  book073.txt  book086.txt  book099.txt
book009.txt  book022.txt  book035.txt  book048.txt  book061.txt  book074.txt  book087.txt  book100.txt
book010.txt  book023.txt  book036.txt  book049.txt  book062.txt  book075.txt  book088.txt
book011.txt  book024.txt  book037.txt  book050.txt  book063.txt  book076.txt  book089.txt
book012.txt  book025.txt  book038.txt  book051.txt  book064.txt  book077.txt  book090.txt
book013.txt  book026.txt  book039.txt  book052.txt  book065.txt  book078.txt  book091.txt

This is super handy!

We can take things a bit further by specifying an interval, to create a number between 1 and 10, counting by two we do:

					

user@server:~/cat$ echo {1..10..2}
1 3 5 7 9

To create by 3, you do:

					

user@server:~/cat$ echo {1..10..3}
1 4 7 10

Just make sure you are using an absolute integer, you can create an actual file, we can use touch together with the interval:

Interval from A..Z

					

user@server: echo {A..Z}
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Interval from A..z

					

pascal@blog:~/cat$ echo {A..z}
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [  ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z

The above would not only cover the capital letter but also the small letters.

You can also use intervals with letters as well:

					

echo {P..Z..2}
P R T V X Z

This would count them in 2’s, to create a backward range, we do:

					

user@server:~/cat$ echo {Z..P..2}
Z X V T R P

 

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