piping symbol / pipe operator in Linux

• ls -l | grep .txt

[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# ls
test1.txt  test2.txt
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# ls -l | grep .txt
-rw-r--r-- 1 root root 211 Sep 30 15:50 test1.txt
-rw-r--r-- 1 root root  30 Sep 30 15:58 test2.txt
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# ls -l | grep .sh
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# 
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# ls -al
total 16
drwxr-xr-x   2 root root 4096 Sep 30 15:58 .
dr-xr-x---. 12 root root 4096 Sep 30 15:58 ..
-rw-r--r--   1 root root  211 Sep 30 15:50 test1.txt
-rw-r--r--   1 root root   30 Sep 30 15:58 test2.txt
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# vim hello.sh
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# ls -l | grep .sh
-rw-r--r-- 1 root root 239 Sep 30 17:16 hello.sh

• cat hello.sh | sort | uniq | grep ‘better’;

[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# cat hello.sh 
hello this is linux
be better
be better
i am lhj
hello this is linux
i am lhj
i am lhj
be better
i am lhj
have a nice day
have a nice day
hello this is linux
hello this is linux
have a nice day
zzzzzzzzzzzzzz
dddddddd
gggggggggggggggggggg
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# cat hello.sh | sort | uniq
be better
dddddddd
gggggggggggggggggggg
have a nice day
hello this is linux
i am lhj
zzzzzzzzzzzzzz
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# cat hello.sh | sort | uniq | grep 'better'
[1] 36048
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.
cat hello.sh | sort | uniq | grep 'better&#39^C
[1]+  Exit 2                  cat hello.sh | sort | uniq | grep --color=auto
[root@iZ2vc5lqzt23aweti4j777Z 30thSep2024]# cat hello.sh | sort | uniq | grep 'better';
be better