Second week homework

1. What are the file management commands on Linux, their commonly used methods and their related examples?

Cat, TAC, head, tail, less, cp,mv,stat

Cat [OPTION] ... [FILE] ...
-N: Displays the number of rows
-E: Display line terminator

[Email protected] tmp]# echo "Hello word" >> 333 [[email protected] tmp]# cat 333hello Word

TAC [OPTION] ... [FILE] ...

[[Email protected] tmp]# TAC 333hello Word

Head
Head [OPTION] ... [FILE] ...
-C #: Specify get before # bytes
-N #: Specifies the first # line to get

Rgqgr[[email protected] tmp]# head 333hello Wordwwqdwqdqqwdqdqdqqwdqwddweqdweewfqfqrrfqfrgqeqqtqtrtqtqfreqgrgegqgqqrgqegqeg[[email protected] tmp]# head-c 50 333hello WORDWWQDWQDQQWDQDQDQQWDQWDDWEQDW

Tail
tail [OPTION] ... [FILE] ...
-C #: Specifies the # bytes after fetching
-N #: Specifies the # line after fetch
-F: Trace displays new additions to the file

[Email protected] tmp]# tail 333qwdqdqdqqwdqwddweqdweewfqfqrrfqfrgqeqqtqtrtqtqfreqgrgegqgqqrgqegqegrgqgrgqqgqgqergegqrgqgqg

Cp

[[email protected] tmp]# cp 333 /var/[[email protected] tmp]# ls  /var/333      cache  cvs  empty  gdm   local  log   nis  preserve  spool  wwwaccount   crash  db   games  lib  lock   mail   opt  run       tmp    yp[[email  protected] tmp]# ls333                   orbit-cpl                   virtual-cpl.grFf4obin                   orbit-gdm                   virtual-cpl.hCmppH                       x

MV

[[EMAIL PROTECTED] TMP]# MV 333 /ETC/[[EMAIL PROTECTED] TMP]# LS1                      mytest1                     virtual-cpl.13la231.txt                 mytest2                     virtual-cpl.7tcqgK2                     mytest3                      virtual-cpl.f57ji7[[email protected] tmp]# ls /etc/333                       hp                              printcapabrt                      httpd                           profileacpi                      idmapd.conf                    profile.d

Stat

[[Email protected] etc]# Stat 333 file: "333" size:122 blocks:8 IO block:4096 Common Files device:fd00h/ 64768d inode:533803 links:1access: (0644/-rw-r--r--) Uid: (0/root) Gid: (0/root) access:2016- 08-14 01:02:40.350008585 +0800modify:2016-08-14 01:02:12.210008511 +0800change:2016-08-14 01:08:54.439008241 +0800

2. Bash's work characteristics the command execution status return value and command line expansion are involved in the content and its sample demonstration.
Bash uses a special variable $? Save the execution status result of the most recent command

0: Success

1-255: Failure

[[email protected] ~]# Pwd/root[[email protected] ~]# echo $?0[[email protected] ~]# Le-bash:le:command not Found[[email Protected] ~]# echo $?127

Command line expansion
~: Expand to the user's home directory
~username: Expand the home directory for the specified user
{}: Can host a comma-delimited list and expand it to multiple paths (multiplication by polynomial)

[Email protected] ~]# LS/TMP/{1,2}/TMP/1:/TMP/2:

3. Use the command line expansion function to complete the following exercises:

(1), create/tmp directory: A_c, A_d, B_c, B_d

[[email protected]/]# mkdir {a,b}_{c,d}

(2), create the/tmp/mylinux directory:

[[Email protected] tmp]# mkdir -pv mylinux/{bin,boot/grb,dev,etc/{rc.d/init.d, Sysconfig/network-scripts},lib/modules,lib64,proc,sbin,sys,tmp,usr/local/{bin,sbin},var,lock,log,run}mkdir:   Created directory   "Mylinux" mkdir:  created directory   "Mylinux/bin" mkdir:  created directory   "Mylinux/boot" mkdir:   Created directory   "MYLINUX/BOOT/GRB" mkdir:  created directory   "Mylinux/dev" mkdir:  created directory   "MYLINUX/ETC" mkdir:  created directory   "MYLINUX/ETC/RC.D" mkdir:  created directory   "MYLINUX/ETC/RC.D/INIT.D" mkdir:  created directory   "Mylinux/etc/sysconfig" mkdir:  created directory   "mylinux/etc/sysconfig/network-scripts" mkdir:  created directory   "Mylinux/lib" mkdir:  created directory   "Mylinux/lib/modules" mkdir:  created directory   "mylinux/lib64" mkdir:   Created directory   "Mylinux/proc" mkdir:  created directory   "Mylinux/sbin" mkdir:  created directory   "Mylinux/sys" mkdir:   Created directory   "mylinux/tmp" mkdir:  created directory   "MYLINUX/USR" mkdir:  created directory   "Mylinux/usr/local" mkdir:  created directory   Mylinux/usr/locAl/bin "mkdir:  created directory  " Mylinux/usr/local/sbin "mkdir:  created directory  " Mylinux/var "mkdir:  created directory   "Mylinux/lock" mkdir:  created directory   "Mylinux/log" mkdir:  created directory   "Mylinux/run" [[email  protected] tmp]# tree mylinux/mylinux/├── bin├── boot│ └── grb├──  dev├── etc│ ├── rc.d│ │ └── init.d│ └── sysconfig│      └── network-scripts├── lib│ └── modules├── lib64├── lock├──  log├── proc├── run├── sbin├── sys├── tmp├── usr│ └── local│      ├── bin│     └── sbin└── var24  Directories, 0 files

4, what is the metadata information of the file, what does it mean, how to view it? How to modify timestamp information for a file.

Files: Made up of metadata and data
Meta Data: Metadate
Statistics: Data
Stat: View metadata information for a specified file

Stat [OPTION] ...          File ...-l: Support for symbolic connection-F: Show filesystem status instead of file status-T: Output information in a concise manner [email protected] tmp]# stat mylinux/file: "mylinux/" size:4096  Blocks:8 IO block:4096 directory device:fd00h/64768d inode:803023 links:17access: (0755/drwxr-xr-x) Uid: (0/root) Gid: (0/root) access:2016-08-13 17:21:16.000000000 +0800modify:2016-08-13 17:16:42.00000 0000 +0800change:2016-08-13 17:34:05.984017941 +0800

File: Name

Size: File size

Blocks: Block

IO Blocks:io Block

Device: File information

Links: Number of hard links

Access: File permissions

Access: Last Accessed time

Modify: Last Change time

Change: Last Modified Time

Touch command:
-A: Modify access time (Atime)
-M: Modification Time (Mtime)
-C: If the file does not exist, it is not created

            three timestamps:
             access time: atime, read file contents
             Modify Time: Modified, Mtime, change file contents (data)
             Change Time: Changes CTime, meta data changes

[[email protected] tmp]# touch-a mylinux/[[email protected] tmp]# stat mylinux/file: "mylinux/" size:4096 Bl    Ocks:8 IO block:4096 directory device:fd00h/64768d inode:803023 links:17access: (0755/drwxr-xr-x) Uid: ( 0/root) Gid: (0/root) access:2016-08-14 00:43:50.305009878 +0800modify:2016-08-13 17:16:42.000000000 +08 00change:2016-08-14 00:43:50.305009878 +0800

5, how to define the alias of a command, how to reference the execution result of another command in the command?
Alias

(1) Alias

Displays all command aliases available in the current shell process

(2) Alias Name= ' VALUE '

Defines the name of the alias, which is equivalent to executing the command value

Attention:

After the definition is only valid for the current shell process, want to be permanently effective, to be defined in the configuration file;

[[email protected] ~]# alias cdnet= ' cd/tmp ' [[email protected] ~]# Cdnet[[email protected] tmp]#

6. Display all files or directories in the/var directory that start with L, end with a lowercase letter, and have at least one digit (can have other characters) appear in the Middle .

[[email protected] ~]# ls-d/var/l*[0-9]*[[:lower:]]

7. Displays files or directories that start with any number in the/etc directory and end with a non-numeric number.

[Email protected] ~]# ls-d/etc/[0-9]*[^0-9]

8, Show/etc directory, start with a non-letter, followed by a letter and any other arbitrary length of any character file or directory.

[Email protected] ~]# ls-d/etc/[^[:alpha:]][[:alpha:]]*

9. In the/tmp directory, create a file that starts with Tfile, followed by the current date and time, with a filename such as: tfile-2016-08-06-09-32-22.

[[email protected]/]# Touch tfile-$ "(Date +%f-%h-%m-%s)"

Or

[[email protected]/]# Touch tfile-$ (date +%f-%h-%m-%s)

10. Copy all the files or directories in the/etc directory to the/tmp/mytest1 directory that begin with P and do not end with a number.

[Email protected]/]# mkdir/tmp/mytest1&&cp-a/etc/p*[^0-9]/tmp/mytest1

11. Copy all files or directories ending with. D in the/etc directory into the/tmp/mytest2 directory.

[Email protected] tmp]# mkdir/tmp/mytest2&&cp-a/etc/*.d/tmp/mytest2

12. Copy all files in the/etc/directory that begin with L or M or N and end with. conf to the/TMP/MYTEST3 directory.

[Email protected] tmp]# mkdir/tmp/mytest3&&cp-a/etc/[l,m,n]*.conf/tmp/mytest3

Or

[Email protected] tmp]# mkdir/tmp/mytest3&&cp-a/etc/[lmn]*.conf/tmp/mytest3

Second week homework