Linux 9th Day Bash Basic command

Linux 9th Day

Time: 20180725

Batch Modify file name

Rename [option] Expression file ...

Rename '. txt '. Bac ' f*.txt can change the f*.txt file suffix to F*.bac

DD If=/dev/zero of=/root/bigfile bs=1m count=100 generate the specified file in the specified directory 100M

Delete large file mode

> filename can instantly free up disk space

Lsof list the files that the process opens

Shred overwrite file hidden content, can be overwritten multiple times

-F forcibly overwrite

-N Multiple overwrite (to prevent recovery of files)

-U deletes the specified file, overwrites the file multiple times, and deletes the file

Xargs is used to assign multiple parameters to a command so that it can execute normally, and adding too many parameters after the default system command will prompt an error

Xargs [OPTION] ... COMMAND

LN creates a hard or soft link

-S Create soft links

Hexdump displaying file contents in ASCII, decimal, hexadecimal, octal mode

-B Display file contents in octal

-C Displays the file contents in ASCII mode

-C Display file contents in 16 and ASCII mode

File Display Type

Set view or set shell variables or positional parameters

[+|-] C settings can overwrite file contents that already exist

TR Convert file characters

Tr ' A-Z ' A-Z ' means converting all lowercase characters to uppercase

-D deletes the specified character

-C Using a reverse reference

-S converts multiple consecutive specified characters to a single character

-T converts the specified character to another character, a bitwise conversion

Dos2unix convert Windows text to linux text, delete \ r

Unix2dos convert Linux files to Windows text, add \ r

SEQ Outputs a sequence

seq [OPTION] ... First INCREMENT Last

-S Specify delimiter

Tee reads from standard input and outputs to standard output and files simultaneously

-A overwrites the original file instead of the default when writing to the file

Mail receives or sends messages

Mail-s SendMail Root <<eof

-S Message header

Users and Groups

Pwunconv the encryption key in the shadow is placed in the/etc/passwd file

Pwconv Recovering Pwunconv Operations

CHFN Modifying the user name's comment information

tree view File Trees

passwd Modifying user passwords

Finger reading User's comment information

Soft links and Hard link differences

1. Soft link Delete the specified file when soft link is not available, hard link Delete any other one can still be used

2. Soft links can create a link to a folder, hard links can not

3. Soft links can be created across file systems, hard links can not

4. Hard links have the same inode number, soft links are not the same

Linux 9th Day Bash Basic command