The | takes the output from the command on the left, and "pipes" it to the command on the right.
The < will take and send the input from the file on the right to the program on the left.
The > takes the output of the command on the left, then writes it to the file on the right.
The >> takes the output of the command on the left, then appends it to the file on the right.
matches anything in a wildcard like *.txt ("anything ending in .txt")
find STARTDIR -name WILDCARD -print
Change PATH for your compute
list out all the environment variables you've found and then go look up what they are online.
Read the man page for env again. What else can it do?
rm `find tmp -maxdepth 1 -name '*.mp3'`
is intended to remove all tmp/*.mp3 files (and ignore any subdirectories), but can fail with an "Argument list too long" message. This exact equivalent:
find tmp -maxdepth 1 -name '*.mp3' -maxdepth 1 | xargs rm
chmod : change mode , change file access permissions
[root@broccoli dhillon]# chmod 777 test1.txt
-rwxrwxrwx 2 root root 247664 May 3 11:39 test1.txt
chmod 644 test1.txt
-rw-r--r-- 2 root root 247664 May 3 11:39 test1.txt
chown = change the owner of a file
ex --> chown bob hello.txt
"substitute user do" or "super user do" . allows a permitted user to execute a command as the superuser or another user (most often the root user)
ex--> sudo bob