Sed Command | Line Replacement | C Programming

Introduction

In this challenge, we will learn how to use the sed command to replace lines in a C file randomly. We will write a script that will randomly delete 20% of the lines from the file and replace them with a string <-- DEL -->. We will also learn how to create random numbers and edit files using the sed command.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL shell(("`Shell`")) -.-> shell/ControlFlowGroup(["`Control Flow`"]) linux(("`Linux`")) -.-> linux/BasicFileOperationsGroup(["`Basic File Operations`"]) linux(("`Linux`")) -.-> linux/BasicSystemCommandsGroup(["`Basic System Commands`"]) linux(("`Linux`")) -.-> linux/InputandOutputRedirectionGroup(["`Input and Output Redirection`"]) linux(("`Linux`")) -.-> linux/TextProcessingGroup(["`Text Processing`"]) shell(("`Shell`")) -.-> shell/BasicSyntaxandStructureGroup(["`Basic Syntax and Structure`"]) shell(("`Shell`")) -.-> shell/VariableHandlingGroup(["`Variable Handling`"]) shell(("`Shell`")) -.-> shell/AdvancedScriptingConceptsGroup(["`Advanced Scripting Concepts`"]) shell(("`Shell`")) -.-> shell/SystemInteractionandConfigurationGroup(["`System Interaction and Configuration`"]) linux(("`Linux`")) -.-> linux/FileandDirectoryManagementGroup(["`File and Directory Management`"]) shell/ControlFlowGroup -.-> shell/if_else("`If-Else Statements`") linux/BasicFileOperationsGroup -.-> linux/cat("`File Concatenating`") linux/BasicFileOperationsGroup -.-> linux/wc("`Text Counting`") linux/BasicSystemCommandsGroup -.-> linux/exit("`Shell Exiting`") linux/BasicSystemCommandsGroup -.-> linux/echo("`Text Display`") linux/InputandOutputRedirectionGroup -.-> linux/pipeline("`Data Piping`") linux/InputandOutputRedirectionGroup -.-> linux/redirect("`I/O Redirecting`") linux/BasicSystemCommandsGroup -.-> linux/printf("`Text Formatting`") linux/TextProcessingGroup -.-> linux/sed("`Stream Editing`") linux/BasicSystemCommandsGroup -.-> linux/bc("`Arithmetic Calculations`") shell/BasicSyntaxandStructureGroup -.-> shell/shebang("`Shebang`") shell/BasicSyntaxandStructureGroup -.-> shell/comments("`Comments`") shell/BasicSyntaxandStructureGroup -.-> shell/quoting("`Quoting Mechanisms`") shell/VariableHandlingGroup -.-> shell/variables_decl("`Variable Declaration`") shell/VariableHandlingGroup -.-> shell/variables_usage("`Variable Usage`") shell/VariableHandlingGroup -.-> shell/str_manipulation("`String Manipulation`") shell/VariableHandlingGroup -.-> shell/arrays("`Arrays`") shell/VariableHandlingGroup -.-> shell/param_expansion("`Parameter Expansion`") shell/ControlFlowGroup -.-> shell/for_loops("`For Loops`") shell/ControlFlowGroup -.-> shell/cond_expr("`Conditional Expressions`") shell/ControlFlowGroup -.-> shell/exit_status("`Exit and Return Status`") shell/AdvancedScriptingConceptsGroup -.-> shell/arith_ops("`Arithmetic Operations`") shell/AdvancedScriptingConceptsGroup -.-> shell/arith_expansion("`Arithmetic Expansion`") shell/AdvancedScriptingConceptsGroup -.-> shell/cmd_substitution("`Command Substitution`") shell/AdvancedScriptingConceptsGroup -.-> shell/subshells("`Subshells and Command Groups`") shell/AdvancedScriptingConceptsGroup -.-> shell/adv_redirection("`Advanced Redirection`") shell/SystemInteractionandConfigurationGroup -.-> shell/globbing_expansion("`Globbing and Pathname Expansion`") linux/FileandDirectoryManagementGroup -.-> linux/wildcard("`Wildcard Character`") subgraph Lab Skills shell/if_else -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/cat -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/wc -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/exit -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/echo -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/pipeline -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/redirect -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/printf -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/sed -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/bc -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/shebang -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/comments -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/quoting -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/variables_decl -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/variables_usage -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/str_manipulation -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/arrays -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/param_expansion -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/for_loops -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/cond_expr -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/exit_status -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/arith_ops -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/arith_expansion -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/cmd_substitution -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/subshells -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/adv_redirection -.-> lab-18872{{"`Random Line Deletion in C Files`"}} shell/globbing_expansion -.-> lab-18872{{"`Random Line Deletion in C Files`"}} linux/wildcard -.-> lab-18872{{"`Random Line Deletion in C Files`"}} end

File Line Replacement Challenge

In this challenge, you are tasked with creating a script to replace 20% of the lines in a C file randomly with a specific pattern.

Tasks

You need to complete the following task:

Provide a .c file to the script through the command-line.
Randomly delete 20% of the lines from the file.
Wherever you delete a line, replace it with the string <-- DEL -->.

Requirements

You must meet the following requirements:

The script should be named replaceLines.sh.
Working directory should be ~/project.
Knowledge about the sed command.
Understanding how to generate random numbers.
Editing files using the sed command.

Example

labex:project/ $ bash replaceLines.sh main.c
[OUTPUT] Number of Lines in the given file main.c : 12 [OUTPUT]
[OUPUT] Number of Lines that need to be replaced: 2 [OUTPUT]
[OUTPUT] lines that are replaced : 4 9 [OUTPUT]

labex:project/ $ cat main.c
#incude <stdio.h>
int main()
{
<---------------- DEL -------------------->
        printf(“Hello world1\n”);
        printf(“Hello world2\n”);
        printf(“Hello world3\n”);
        printf(“Hello world4\n”);
<---------------- DEL -------------------->
        printf(“Hello world6\n”);
        #...
}

Random Line Deletion in C Files