52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
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// Outputs contents of file and connects a pipe to a child process
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// which runs the "less" pager program.
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//
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// Adapted from Stevens/Rago Figure 15.11 "Copy file to pager program
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// using popen"
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#include <stdio.h>
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#include <limits.h>
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#include <stdlib.h>
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#include <sys/wait.h>
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#define MAXLINE 1024
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#define PAGER "less" // environment variable, or default
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// #define PAGER "${PAGER:-more}" // environment variable, or default
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int main(int argc, char *argv[]) {
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char line[MAXLINE];
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FILE *fpin, *fpout;
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if (argc != 2){
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printf("usage: a.out <file>\n");
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exit(1);
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}
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if ((fpin = fopen(argv[1], "r")) == NULL){
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perror("can′t open input file");
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exit(1);
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}
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if ((fpout = popen(PAGER, "w")) == NULL){
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perror("popen error");
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exit(1);
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}
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// copy argv[1] to pager
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while (fgets(line, MAXLINE, fpin) != NULL) {
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if (fputs(line, fpout) == EOF){
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perror("fputs error to pipe");
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exit(1);
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}
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}
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if (ferror(fpin)){
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perror("fgets error");
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exit(1);
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}
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if (pclose(fpout) == -1){
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perror("pclose error");
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exit(1);
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}
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return 0;
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}
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