Let us look at a folder with many subfolders and files.

[]$ cd ~/intro_to_linux
[intro_to_linux]$ ls
clusters  data  fruits.txt  software.csv  vegatables.txt  workshop_all.txt  workshop_me.txt

The ls by default only lists the first level of folders and files.

What does the -R option do?

[intro_to_linux]$ ls -R
.:
clusters  data  fruits.txt  software.csv  vegatables.txt  workshop_all.txt  workshop_me.txt
./clusters:
beartooth.html  loren.html  teton.html  wildiris.html
./data:
2021  2022  2023  dd.tx
./data/2021:
Apr  feb  Nov  README.txt  Sep
./data/2021/Apr:
20210403.txt  20210427.txt  20210428.txt
./data/2021/feb:
february_01_2021.tx
./data/2021/Nov:
20211114.txt  20211115.txt  20211116.txt  hello.txt

./data/2021/Sep:
20210908.txt  20210921.txt
./data/2022:
Dec  February  Hello.csv  Jul  Jun  readme.txt
./data/2022/Dec:
20221207.txt  20221220.txt  20221230.txt  20221231.txt  2022_dec_01.txt
./data/2022/February:
20220203.txt  20220223.txt
./data/2022/Jul:
20220720.txt  20220722.txt  20220723.TX
./data/2022/Jun:
20220611.txt  20220615.txt  20220624.txt
./data/2023:
Feb  Jan  Mar  ReadMe.txt
./data/2023/Feb:
20230204.txt  20230217.txt  20230223.txt  20230224.txt
./data/2023/Jan:
20230102.txt  20230108.txt  20230115.txt  20230121.txt  texttx
./data/2023/Mar:
20230305.txt  20230311.txt  20230313.txt  20230326.txt  20230327.txt  HELLO.txt
./data/dd.tx:

Check the manual page:

[]$ man ls
...
       -R, --recursive
              list subdirectories recursively
...

The find command is naturally recursive.

Find the file named: 20230121.txt

[]$ cd ~/intro_to_linux/
[intro_to_linux]$ find . -name 20230121.txt
./data/2023/Jan/20230121.txt

# Check that this file is within the returned location.
[intro_to_linux]$ ls data/2023/Jan/
20230102.txt  20230108.txt  20230115.txt  20230121.txt

Find the file named: 20230120.txt

[intro_to_linux]$ find . -name 20230120.txt
[intro_to_linux]$

The command completed since we got back to the prompt and no errors were displayed.

No output means that this file could not be found.

The find command is case-sensitive. Find the file with the exact filename README.txt

[intro_to_linux]$ find . -name README.txt
./data/2021/README.txt

Use the alternative -iname option to search for a file name that is case-insensitive:

[intro_to_linux]$ find . -iname README.txt
./data/2021/README.txt
./data/2022/readme.txt
./data/2023/ReadMe.txt

Use wildcards to find all files with the postfix .csv:

Lets look at two versions:

With quotes:

[intro_to_linux]$ find . -name "*.csv"
./software.csv
./data/2022/Hello.csv

Without quotes:

[intro_to_linux]$ find . -iname *.csv
./software.csv

Using or not using quotes across commands is an advanced and confusing subject.

If you do not use quotes, then if you have a file in the current directory ending with .csv, the wildcard is essentially expanded by the shell.

So, if you have a file named say "software.csv" (which we do), the command that gets executed is find . -name software.csv.

Find any files/folders that contain the string dec. Case-sensitive versus case-insensitive.

[intro_to_linux]$ find . -name "*dec*"
./data/2022/Dec/2022_dec_01.txt

[intro_to_linux]$ find . -iname "*dec*"
./data/2022/Dec
./data/2022/Dec/2022_dec_01.txt

Find only folders using the type option and d for only directory.

Question: Are we searching with respect to case-sensitive or insensitive?

[intro_to_linux]$ find . -type d -iname "*dec*"
./data/2022/Dec

Find only files using the f (for file) value for the type option.

[intro_to_linux]$ find . -type f -iname "*dec*"
./data/2022/Dec/2022_dec_01.txt

Questions:

1. What do we notice about some of the find command options?

2. Find any files that contain the string “hello”, regardless of case, within their filename.

3. Find any folders or files that contain the string “feb” regardless of case.

   1. Can you list only the folders?

4. Find any files that have the postfix “tx” – must be lowercase.

1. What do we notice about some of the find command options?

2. Find any files that contain the string “hello”, regardless of case, within their filename.

[intro_to_linux]$ find . -name "hello"

[intro_to_linux]$ find . -name "hello.*"
./data/2021/Nov/hello.txt

[intro_to_linux]$ find . -iname "hello.*"
./data/2021/Nov/hello.txt
./data/2022/Hello.csv
./data/2023/Mar/HELLO.txt

3. Find any folders or files that contain the string “feb” regardless of case.

• Can you list only the folders?

[intro_to_linux]$ find . -name feb
./data/2021/feb
[intro_to_linux]$ find . -iname feb
./data/2021/feb
./data/2023/Feb
[intro_to_linux]$ find . -iname "*feb*"
./data/2021/feb
./data/2021/feb/february_01_2021.tx
./data/2022/February
./data/2023/Feb
[intro_to_linux]$ find . -type d -iname "*feb*"
./data/2021/feb
./data/2022/February
./data/2023/Feb

4. Find any files that have the postfix “tx” – must be lowercase.

[intro_to_linux]$ find . -name "tx"

[intro_to_linux]$ find . -name "*tx*"
./data/2021/README.txt
./data/2021/Nov/20211115.txt
./data/2021/Nov/hello.txt
./data/2021/Nov/20211114.txt
…
[intro_to_linux]$ find . -name "*tx"
./data/dd.tx
./data/2021/feb/february_01_2021.tx
./data/2023/Jan/texttx
[intro_to_linux]$ find . -name "*.tx"
./data/dd.tx
./data/2021/feb/february_01_2021.tx

Notice: dd.tx is actually a folder, defined by the ’d’ in the long format list.

[intro_to_linux]$ ls -l data
total 4
drwxrwxr-x 6 <username> <username> 2021
drwxrwxr-x 6 <username> <username> 2022
drwxrwxr-x 5 <username> <username> 2023
drwxrwxr-x 2 <username> <username> dd.tx

[intro_to_linux]$ find . -type f -name "*.tx"
./data/2021/feb/february_01_2021.tx

If we (forget and) ignore the case (using iname), we would see:

[intro_to_linux]$ find . -type f -iname "*.tx"
./data/2021/feb/february_01_2021.tx
./data/2022/20220723.TX

Notice this has listed a file with a capital a postfix .TX - this is not what we wanted.