tac headache

To view the content in the file, you can use many commands. Today I will introduce several commonly used commands for viewing the file content. Of course, there is an ace command (Tool) vim on the Linux system. The use of this tool has been described in detail in vi/vim, you can also edit it easily. Today, we mainly look at the content in the file, not editing it. Common commands for viewing File Content Cat displays the file content starting with the first line

tively setting it to null. Note that this command does not affect positional parameters 9. The export Command makes availables to all child processes of the running script or shell. Unfortunately, there is no way to export variables back to the parent process, The process that called or invoked the script or shell. One import use of the Export command is in startup files, to initialize and make accessible environmental variables to subsequent user processes. 10. Jobs command Lists the

sides of a national border (different provinces in China). It is xy1y2. X: Operator (Post and Telecommunications x = 1, China Unicom = 0) Y1 and Y2: distribution is shown in Table 5-1. Table 5-1 y1y2 allocation Y2 Y101 0Jilin, Gansu, Tibet, Guangxi, Fujian, Hubei, Beijing, and SusuHeilongyi, Liaoning, Ningxia, Sichuan, Hainan, xianxi, Tianjin, Shanxi, and Shandong 1Xinjiang, Guangdong, Hebei, Anhui, Shanghai, Guizhou, and ShaanxiInner Mongolia, Qinghai, Yunnan, Henan, Zhejiang, AND HUNAN NCC =

network is 0l. Msin = Mobile customer identification code, which consists of 11 digits. Uniquely identifies China Mobile clients in China's GSM mobile communication network. International mobile device identification code (IMEI) Uniquely identifies the code of a mobile device, which is a 15-digit decimal number. Its structure is: 6-digit, 2-digit, 6-digit, L-digit, Tac fac snr sp tac = model approval code,

structure is: 3bit 3bit NCC BCC | -------- Bsic ------------- | NCC = a national color code. It is mainly used to differentiate operators on different sides of a national border (different provinces in China). It is xy1y2. X: Operator (Post and Telecommunications x = 1, China Unicom = 0) Y1 and Y2: distribution is shown in Table 5-1. Table 5-1 y1y2 allocation Y2 Y101 0Jilin, Gansu, Tibet, Guangxi, Fujian, Hubei, Beijing, and SusuHeilongyi, Liaoning, Ningxia, Sichuan, Hainan, xianxi, Tianjin, Sh

unique.Structure:IMEI = TAC + FAC + SNR + SP (15 digits)The TAC model approval code is assigned by the European model approval center with the first two country codesThe final assembly code of FAC indicates that the factory or the final assembly location is encoded by the manufacturer.The SNR serial number uniquely identifies each TAC and FAC mobile deviceSP-Spa

Linux Study Notes 2_mysql installation, Study Notes 2_mysql There are many commands for viewing file content: cat, tac, more, less, head, tail, nl. Cat displays the file content from the first line. tac displays the file content from the last line. You can see that tac is a reverse write of cat. more displays the file content on one page; less is similar to more,

: rmdir 40 original definition: remove empty directories 41 path:/bin/rmdir 42 Syntax: rmdir [directory name] // you can only delete an empty directory 43 44 // directory processing command: cp 45 Original Definition: copy 46 path:/bin/cp 47 Syntax: cp-rp [original file or directory] [target directory] // copy Copy copy 48-r copy directory 49-p keep file attributes 50 51 // directory processing command: mv 52 Original Definition: move 53 path:/bin/mv 54 Syntax: mv [original file or directory] [t

TAB 4. Command instance: Instance 1:Output The log22.txt file content and add the row number Command: cat-n log22.txt log33.txt Example 2:Merge the contents of the two files and add the row number. Command: cat-B log22.txt log33.txt Note: add the line numbers of the log22.txtand log33.txt files and print them to the screen. Example 3:Add the row number of the file content and input it to another file. Command: cat-n log22.txt> log. log Note: add the log22.txt file with the row number and inp

period of time-time is a configurable parameter. This is the screen when tload is running: Tload: Can you see the changes in the system load? Segfault debugging ASSISTANT: catchsegv Catchsegv can help people diagnose program "segment errors (BKJIA edit Note: segmentation fault, segfault. This error is common in C Programs and is usually caused by access to invalid memory addresses )". If you are processing an application that frequently shows "segfault", start it with catchsegv and observe the

(range. Man makes it clearer. The row [plain] $ cat test.txt line1 line2 line3 line4 line5 line6 $ sed-n '/[1-3]/is not printed. P'test.txt line4 line5 line6 let's look at a complex example and reverse the text 1) First sed reads the first row to the mode space and then copies it to the hold space 2) then sed reads the second row to the mode space and appends the reserved space to the mode space (the mode space is now the second row and the first row ), copy the mode space to the hold space and

: displays the end symbol of a row $Example: cat-n/etc/fstab -- View/etc/fatab content and display the row number-- Tac: view text content in flashbackFormat: tac [OPTION]... [FILE]...Example: tac/etc/passwd -- view text content in flashback-- Head: displays text. The first 10 lines are displayed by default.Format: head [OPTION]... [FILE]...-N #: show text header

will be updated only when the source is switched to a new one.4. Check the file contentCommands for viewing file content include:Cat: displays the file content starting from the first line;Tac: displays the file content from the last line;Nl: displays the row number of the table;More: displays the file content one page at a time;Less: similar to more, and you can flip the page forward;Head: only the first few rows;Tail: only the last few rows;Od: Rea

Game 566.11 Chapter Summary 57The 7th chapter uses the debugger 587.1 bug! 587.2 Debugger 597.3 Stepping 617.4 Find Bug 637.5 Breakpoint 667.6 Example of using breakpoints 677.7 Chapter Summary 688th Chapter Flowchart 698.1 How to play Hangman 698.2 Hangman Run Example 698.3 ASCII word metalized 718.4 Use flowchart to design a program 718.5 Generating Flowchart 738.6 Chapter Summary 799th Chapter Hangman 81Source code for 9.1 Hangman 819.2 Multi-line string 869.3 Constant 869.4 List 869.5 Metho