This book is divided into five parts, which introduces shell programming skills, various UNIX commands and syntax in detail, and also involves word processing under UNIX and a small number of system management issues. This book is comprehensive in content and concise and smooth in text, making it suitable for Shell programmers to learn and refer to.
Table of Contents Translator's Preface Part One Shell
Chapter 1 File Security and Permissions 1
1.1 Document 1
1.2 File Type 2
1.3 Permission 2
1.4 Change permission bit 4
1.4.1 Symbol Mode 4
1.4.2 chmod command example 5
1.4.3 Absolute mode 5
1.4.4 Other examples of chmod command 6
1.4.5 You can choose to use symbolic mode or absolute mode 7
1.5 Contents 7
1.6 suid/guid 7
1.6.1 Why use suid/guid 8
1.6.2 Example of setting suid/guid 8
1.7 chown and chgrp 9
1.7.1 chown example 9
1.7.2 chgrp example 9
1.7.3 Find out which user groups you belong to 9
1.7.4 Find out which groups other users belong to10
1.8umask 10
1.8.1 How to calculate the umask value 10
1.8.2 Commonly used umask value 11
1.9 Symbolic links 12
1.9.1 Using soft links to save multiple images of a file 12
1.9.2 Symbolic link example 12
1.10 Summary 13
Chapter 2 Using find and xargs 14
2.1 find command options 14
2.1.1 Using name option 15
2.1.2 Using perm option 16
2.1.3 Ignore a directory 16
2.1.4 Using the user and nouser options 16
2.1.5 Using the group and nogroup options 16
2.1.6 Find files based on change time 17
2.1.7 Find files newer or older than a certain file 17
2.1.8 Using type option 17
2.1.9 Using size option 18
2.1.10 Using depth option 18
2.1.11 Using mount option 18
2.1.12 Using cpio option 18
2.1.13 Use exec or ok to execute shell commands 19
2.1.14 Example 20 of find command
2.2 xargs 20
2.3 Summary 21
Chapter 3 Executing Commands in the Background 22
3.1 cron and crontab 22
3.1.1 crontab domain 22
3.1.2 Examples of crontab entries 23
3.1.3 crontab command option 23
3.1.4 Create a new crontab file 24
3.1.5 List crontab files 24
3.1.6 Edit crontab file 24
3.1.7 Delete crontab file 25
3.1.8 Recover lost crontab files 25
3.2 at command 25
3.2.1 Use the at command to submit commands or scripts 26
3.2.2 List submitted assignments 27
3.2.3 Clear a job 27
3.3 & Command 27
3.3.1 Submit command to the background 28
3.3.2 Use the ps command to view the process 28
3.3.3 Kill background processes 28
3.4 nohup command 29
3.4.1 Use the nohup command to submit jobs 29
3.4.2 Submit several jobs at once 29
3.5 Summary 30
Chapter 4 File Name Replacement 31
4.1 Use* 31
4.2 Use? 32
4.3 Using [...] and [!...] 32
4.4 Summary 33
Chapter 5 Shell Input and Output 34
5.1 echo 34
5.2 read 35
5.3 cat 37
5.4 Pipeline 38
5.5 tee 39
5.6 Standard input, output, and errors 40
5.6.1 Standard input 40
5.6.2 Standard output 40
5.6.3 Standard error 40
5.7 File Redirection 40
5.7.1 Redirecting standard output 41
5.7.2 Redirecting standard input 42
5.7.3 Redirecting standard error 42
5.8 Using standard output and standard error together 43
5.9 Merging standard output and standard error 43
5.10 exec 44
5.11 Using file descriptors 44
5.12 Summary 45
Chapter 6 Command Execution Sequence 46
6.1 Using && 46
6.2 Use || 46
6.3 Use () and { } to combine commands 47
6.4 Summary 48
Part 2 Text Filtering Chapter 7 Introduction to Regular Expressions 49
7.1 Using periods to match single characters 50
7.2 Match a string or character sequence with ^ at the beginning of the line 50
7.3 Match string or character 51 with $ at end of line
7.4 Use * to match a single character or its repeated sequence in a string 51
7.5 Use to mask the meaning of a special character 52
7.6 Use [] to match a range or set52
7.7 Use {} to match the number of times the pattern result appears 53
7.8 Summary 55
Chapter 8 grep family 56
8.1 grep 57
8.1.1 Double quotation marks 57
8.1.2 grep option 57
8.1.3 Query multiple files 57
8.1.4 Line Match 57
8.1.5 Number of lines 58
8.1.6 Displaying non-matching lines 58
8.1.7 Exact match 58
8.1.8 Case sensitivity58
8.2 grep and regular expressions 58
8.2.1 Mode range 59
8.2.2 Does not match beginning of line 59
8.2.3 Set case 59
8.2.4 Match any character 59
8.2.5 Date query 59
8.2.6 Range combination 60
8.2.7 Pattern appearance probability 60
8.2.8 Use grep to match “AND” or “OR” patterns 61
8.2.9 Blank line 61
8.2.10 Match special characters 61
8.2.11 Query formatted file name 61
8.2.12 Query IP address 61
8.3 Class name 62
8.4 System grep command 62
8.4.1 Table of Contents 63
8.4.2 passwd file 63
8.4.3 Using the ps command 63
8.4.4 Using grep 64 on a string
8.5 egrep 64
8.6 Summary 65
Chapter 9 Introduction to AWK 66
9.1 Calling awk 66
9.2 awk script 67
9.2.1 Patterns and Actions 67
9.2.2 Domains and records 67
9.2.3 Regular expressions and their operations in awk 70
9.2.4 Metacharacters 70
9.2.5 Conditional operators 70
9.2.6 awk built-in variables 73
9.2.7 NF, NR and FILENAME 74
9.2.8 awk operator 75
9.2.9 Built-in string functions 78
9.2.10 String masking sequence 80
9.2.11 awk output function printf 81
9.2.12 printf modifier 81
9.2.13 awk array 86
9.3 Summary 88
Chapter 10 Introduction to sed Usage 89
10.1 How to read data with sed 89
10.2 Calling sed 89
10.2.1 Saving sed output 90
10.2.2 How to use sed to query text in a file 90
10.2.3 Basic sed editing commands 90
10.3 sed and regular expressions 91
10.4 Basic sed programming examples 91
10.4.1 Using p(rint) to display line 91
10.4.2 Print range 91
10.4.3 Print mode 92
10.4.4 Querying using patterns and line numbers 92
10.4.5 Matching metacharacters 92
10.4.6 Displaying the entire file 92
10.4.7 Any character 92
10.4.8 First line 92
10.4.9 Last line 93
10.4.10 Print line number 93
10.4.11 Additional text 93
10.4.12 Create sed script file 94
10.4.13 Inserting text 94
10.4.14 Modify text 95
10.4.15 Delete text 96
10.4.16 Replacement text 96
10.5 Modifying strings using substitution 97
10.6 Write sed results to file command 97
10.7 Reading text from a file 98
10.8 Exit 98 after matching
10.9 Displaying control characters in files 99
10.10 Using system sed 99
10.10.1 Handling control characters 99
10.10.2 Processing message output 101
10.10.3 Remove the number 101 at the beginning of the line
10.10.4 Additional text 102
10.10.5 Passing value 102 from shell to sed
10.10.6 Setting shell variables from sed output 102
10.11 Quick one-line commands 102
10.12 Summary 103
Chapter 11 Merger and Split 104
11.1 sort usage 104
11.1.1 Overview 104
11.1.2 sort options 104
11.1.3 Saving output 105
11.1.4 sort startup method 105
11.1.5 How sort refers to domains 105
11.1.6 Whether the file has been classified105
11.1.7 Basic sort 106
11.1.8 sort classification inversion 106
11.1.9 Classification by designated domain 106
11.1.10 Numerical field classification 106
11.1.11 Uniqueness classification 107
11.1.12 Other sort methods using k 108
11.1.13 Using k for classification key sorting 108
11.1.14 Specify sort sequence 108
11.1.15 pos usage 108
11.1.16 Classify output using head and tail 109
11.1.17 awk uses sort to output results 109
11.1.18 Merge two classification files 110
11.2 System sort 110
11.3 uniq usage 111
11.4 join usage 112
11.5 cut usage 114
11.5.1 Using domain separators 115
11.5.2 Cut the specified field 115
11.6 paste usage 116
11.6.1 Specifying columns 116
11.6.2 Using different field delimiters 116
11.6.3 paste command pipeline input 117
11.7 split usage 117
11.8 Summary 118
Chapter 12 tr Usage 119
12.1 About tr 119
12.1.1 Character range 119
12.1.2 Saving output 120
12.1.3 Removing repeated characters 120
12.1.4 Delete empty lines 120
12.1.5 Uppercase to lowercase 121
12.1.6 Lowercase to uppercase 121
12.1.7 Delete specified characters 121
12.1.8 Converting control characters 122
12.1.9 Quick conversion 122
12.1.10 Matching more than one character 123
12.2 Summary 123
Part 3 Login Environment Chapter 13 Login Environment 125
13.1 /etc/profile 125
13.2 User’s $HOME.profile 128
13.3 stty usage 129
13.4 Create .logout file 131
13.5 Summary 131
Chapter 14 Environment and Shell Variables 132
14.1 What are shell variables132
14.2 Local variables 132
14.2.1 Display variables 133
14.2.2 Clear variables 133
14.2.3 Display all local shell variables 133
14.2.4 Combining variable values 134
14.2.5 Testing whether a variable has been set 134
14.2.6 Use variables to save system command parameters 135
14.2.7 Setting read-only variables 135
14.3 Environment variables 136
14.3.1 Setting environment variables 136
14.3.2 Display environment variables 136
14.3.3 Clear environment variables 137
14.3.4 Embedding shell variables 137
14.3.5 Other environment variables 139
14.3.6 set command 140
14.3.7 Exporting variables to child processes 140
14.4 Positional variable parameters 141
14.4.1 Using positional parameters in scripts 142
14.4.2 Passing parameters to system commands 142
14.4.3 Specific variable parameters 143
14.4.4 Final exit status 144
14.5 Summary 145
Chapter 15 Quotes 146
15.1 Necessity of citation 146
15.2 Double quotes 146
15.3 Single quotes 147
15.4 Backticks147
15.5 Backslash 148
15.6 Summary 149
Part 4 Basic Shell Programming Chapter 16 Introduction to Shell Scripts 151
16.1 Reasons to use shell scripts 151
16.2 Script content 151
16.3 Running a script 152
16.4 Summary 153
Chapter 17 Conditional Testing 154
17.1 Test file status 154
17.2 Using logical operators when testing 155
17.3 String testing 155
17.4 Test value 156
17.5 expr usage 157
17.5.1 Incremental counting 158
17.5.2 Numerical testing 158
17.5.3 Pattern matching 158
17.6 Summary 159
Chapter 18 Control Flow Structures 160
18.1 Exit status 160
18.2 Control Structure 160
18.2.1 Flow control 161
18.2.2 Loops 161
18.3 if then else statement 161
18.3.1 Simple if statement 162
18.3.2 Variable value testing 162
18.3.3 grep output inspection 163
18.3.4 Testing grep output with variables 163
18.3.5 File copy output check 164
18.3.6 Current directory test 164
18.3.7 File permission testing 165
18.3.8 Testing parameters passed into scripts 165
18.3.9 Determining whether the script is in interactive mode165
18.3.10 Simple if else statement 166
18.3.11 Variable setting test 166
18.3.12 Detecting the user running the script 166
18.3.13 Pass script parameters into system commands 167
18.3.14 null: command usage 167
18.3.15 Test directory creation results 168
18.3.16 Another copy instance 169
18.3.17 Multiple if statements 169
18.3.18 Testing and setting environment variables 169
18.3.19 Detecting the last command status 170
18.3.20 Adding and checking integer values 171
18.3.21 Simple secure login script 172
18.3.22 elif usage 173
18.3.23 Using elif for multi-condition detection 173
18.3.24 Multiple file location detection 174
18.4 case statement 175
18.4.1 Simple case statement 175
18.4.2 Using match patterns | 176
18.4.3 Prompt to type y or n 177
18.4.4 case and command parameter passing 177
18.4.5 Capturing input and executing an empty command 178
18.4.6 Default variable values 179
18.5 for loop 180
18.5.1 Simple for loop 181
18.5.2 Printing a string list 181
18.5.3 Using the ls command with a for loop 181
18.5.4 Using parameters with for loops 182
18.5.5 Using for loop to connect to the server 183
18.5.6 Using for loop to back up files 183
18.5.7 Multiple file conversion 183
18.5.8 Multiple sed deletion operations 184
18.5.9 Loop Count 184
18.5.10 for loops and local documents 184
18.5.11 for loop embedding 185
18.6 until loop 186
18.6.1 Simple until loop 186
18.6.2 Monitoring files 187
18.6.3 Monitoring disk space 187
18.7 while loop 188
18.7.1 Simple while loop 188
18.7.2 Use while loop to read keyboard input 188
18.7.3 Reading data from a file using a while loop 189
18.7.4 Reading files using IFS 189
18.7.5 File processing with test conditions 190
18.7.6 Scanning file lines for count 191
18.7.7 Reading a pair of records at a time 193
18.7.8 Ignore the # character 193
18.7.9 Processing formatted reports 194
18.7.10 while loops and file descriptors 196
18.8 Using break and continue to control loops 197
18.8.1 break 197
18.8.2 Jump out of case statement 197
18.8.3 continue 197
18.8.4 Browsing file lines 198
18.9 Menu 199
18.10 Summary 201
Chapter 19 Shell Functions 202
19.1 Defining functions in scripts 203
19.2 Using functions in scripts 203
19.3 Passing parameters to functions 203
19.4 Returning 203 from the calling function
19.5 Function return value testing 204
19.6 Using functions in the shell 204
19.7 Creating function files 204
19.8 Locating files 205
19.9 Checking Loading Functions 205
19.10 Executing shell functions 205
19.10.1 Delete shell function 206
19.10.2 Editing shell functions 206
19.10.3 Function examples 207
19.10.4 Grouping functions together 219
19.11 Function calls 219
19.11.1 Calling functions in scripts 219
19.11.2 Calling functions from function files 220
19.12 Locating files isn’t just for functions 222
19.13 Summary 223
Chapter 20 Passing Parameters to Scripts 224
20.1 shift command 225
20.1.1 Simple usage of shift command 225
20.1.2 The last parameter entered on the command line 225
20.1.3 Using shift to process file conversion 226
20.2 getopts 229
20.2.1 getopts script example 229
20.2.2 How to use getopts 231
20.2.3 Use getopts to specify variable values 231
20.2.4 Access value method 232
20.2.5 Using getopts to handle file conversion 233
20.3 Summary 235
Chapter 21 Creating Screen Output 236
21.1 tput usage 236
21.1.1 String output 236
21.1.2 Digital output 237
21.1.3 Boolean output 237
21.2 tput usage 237
21.2.1 Setting the tput command 237
21.2.2 Using Boolean output 237
21.2.3 Using tput in scripts 237
21.2.4 Generating escape sequences 238
21.2.5 Cursor position 239
21.2.6 Displaying text in the center of the screen 240
21.2.7 Finding terminal attributes 240
21.2.8 Using function keys in scripts 241
21.2.9 Using Color 242
21.2.10 Generating Color 243
21.2.11 Create exquisite menu 246
21.3 Summary 251
Chapter 22 Creating screen input 252
22.1 Add records 252
22.2 Delete records 262
22.3 Modification records 266
22.4 View records 270
22.5 Summary 273
Chapter 23 Debugging Scripts 274
23.1 General Errors 274
23.1.1 Loop error 274
23.1.2 Typical missing quotation marks 274
23.1.3 Test Error 274
23.1.4 Character case 275
23.1.5 for loop 275
23.1.6 echo 275
23.2 set command 275
23.3 Summary 276
Chapter 24 Shell Embedding Commands 277
24.1 Complete list of shell embedded commands 277
24.1.1 pwd 277
24.1.2 set 278
24.1.3 times 278
24.1.4 type 278
24.1.5 ulimit 279
24.1.6 wait 279
24.2 Summary 279
Part 5 Advanced Shell Programming Techniques Chapter 25 In-depth Discussion
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