Linux shell basic2 cat find tr
Cat stands for concatenate.
Case 1.
When the text files have more blank lines, we want to remove them.
We can use regex \s+ '\n'.
cat file.txt | tr \s '\n'
cat -T file.txt # show tabs as ^.
cat -n file.txt # show line numbers
. Specifies current directory and .. Specifies the parent directory. This convention is followed throughout the Unix file system.
find . -iname "*.txt"
i means ignore the case.
find . \( -name "*.txt" -o -name "*.pdf" \) -print
./text.pdf
./new.txt
find . -iregex ".*\(\.py\|\.sh\)$"
./test.py
./new.PY
find . ! -name "*.txt" -print
Files not end with .txt.
find . -maxdepth 1 -type f -print
Just show file and not traverse the sub folder.
find . -type d
Just show the directory
Type :
f : file
d: directory
l: link
Print all the files that were accessed within the last 7 days as follows:
$ find . -type f -atime -7 -print
atime: access time
mtiem: modify time
-ctime:change time
n order to print all the files that are having access time older than seven minutes, use the
following command:
$ find . -type f -amin +7 -print
For example, find all the files that are having a modification time greater than that of the
modification time of a given file.txtfile as follows:
$ find . -type f -newer file.txt -print
Search based on file size
Based on the file sizes of the files, a search can be performed as follows:
$ find . -type f -size +2k
# Files having size greater than 2 kilobytes
Instead of kwe can use different size units as the following:
b– 512 byte blocks
c– bytes
w– two byte words
k– Kilobyte
M– Megabyte
G– Gigabyte
find . -type f -name "*.c" -exec cat {} \;>all_c_files.txt
$ cat example.txt # Example file
1 2 3 4 5 6
7 8 9 10
11 12
$ cat example.txt | xargs
1 2 3 4 5 6 7 8 9 10 11 12
$ cat example.txt | xargs -n 3
1 2 3
4 5 6
7 8 9
10 11 12
echo "hello linux" | tr 'a-z' 'A-Z'
HELLO LINUX
echo "Hello 123 world 456" | tr -d '0-9'
Hello world
echo hello 1 char 2 next 4 | tr -d -c '0-9 \n'
1 2 4
echo "I am your friends?" | tr -s ' '
I am your friends?
find -type f | xargs md5sum
e8bc686b2c380b9ad56c024a03384150 ./sub/java.txt
a5bf231497e5d503172bfd39a387b197 ./all_txt_files.txt
e827b6437257f24b9e5fbba44fd98f5c ./num.txt
b6d9275e7e16b154059677fac91baa79 ./test.txt
b6d9275e7e16b154059677fac91baa79 ./mul_bank.txt
sort -r : sort in reverse order
Split can used to split file to specify size.