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Top Forums Shell Programming and Scripting How to delete lines starting with specific string? Post 302911089 by balajesuri on Wednesday 30th of July 2014 03:14:42 AM
Old 07-30-2014
IMHO, awk seems to be the candidate for this job. Use awk to read the title and the next line (using getline function). If the 2nd line (fetched using getline) doesn't start with N, print title and the next line, else skip to the next title.

Let us know what you have tried.
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GETLINE(3)						     Linux Programmer's Manual							GETLINE(3)

NAME
getline, getdelim - delimited string input SYNOPSIS
#include <stdio.h> ssize_t getline(char **lineptr, size_t *n, FILE *stream); ssize_t getdelim(char **lineptr, size_t *n, int delim, FILE *stream); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getline(), getdelim(): Since glibc 2.10: _POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700 Before glibc 2.10: _GNU_SOURCE DESCRIPTION
getline() reads an entire line from stream, storing the address of the buffer containing the text into *lineptr. The buffer is null-termi- nated and includes the newline character, if one was found. If *lineptr is NULL, then getline() will allocate a buffer for storing the line, which should be freed by the user program. (In this case, the value in *n is ignored.) Alternatively, before calling getline(), *lineptr can contain a pointer to a malloc(3)-allocated buffer *n bytes in size. If the buffer is not large enough to hold the line, getline() resizes it with realloc(3), updating *lineptr and *n as necessary. In either case, on a successful call, *lineptr and *n will be updated to reflect the buffer address and allocated size respectively. getdelim() works like getline(), except that a line delimiter other than newline can be specified as the delimiter argument. As with get- line(), a delimiter character is not added if one was not present in the input before end of file was reached. RETURN VALUE
On success, getline() and getdelim() return the number of characters read, including the delimiter character, but not including the termi- nating null byte (''). This value can be used to handle embedded null bytes in the line read. Both functions return -1 on failure to read a line (including end-of-file condition). In the event of an error, errno is set to indicate the cause. ERRORS
EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid). VERSIONS
These functions are available since libc 4.6.27. CONFORMING TO
Both getline() and getdelim() were originally GNU extensions. They were standardized in POSIX.1-2008. EXAMPLE
#define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> int main(void) { FILE *fp; char *line = NULL; size_t len = 0; ssize_t read; fp = fopen("/etc/motd", "r"); if (fp == NULL) exit(EXIT_FAILURE); while ((read = getline(&line, &len, fp)) != -1) { printf("Retrieved line of length %zu : ", read); printf("%s", line); } free(line); exit(EXIT_SUCCESS); } SEE ALSO
read(2), fgets(3), fopen(3), fread(3), gets(3), scanf(3) COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. GNU
2013-04-19 GETLINE(3)
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