getaliasent_r - Linux

Overview

getaliasent_r retrieves the next alias entry from the file /etc/aliases. It is commonly used in C programs to loop through the alias file and extract alias names and expansions.

Syntax

int getaliasent_r(Aliasent *resultbuf, char *buffer, size_t buflen, char **aliasep);

Options/Flags

  • resultbuf: Pointer to an Aliasent structure to store the alias data.
  • buffer: Buffer to hold the alias line read from the file.
  • buflen: Size of the buffer.
  • aliasep: Pointer to a pointer to the alias name.

Examples

Example 1: Get the next alias entry

Aliasent *resultbuf;
char buffer[1024];
char *aliasep;

while ((getaliasent_r(resultbuf, buffer, sizeof(buffer), &aliasep) == 0) && aliasep) {
    printf("Alias: %s, Expansion: %s\n", aliasep, resultbuf->alias);
}

Example 2: Get a specific alias by name

Aliasent *resultbuf;
char buffer[1024];
char *aliasep;

while ((getaliasent_r(resultbuf, buffer, sizeof(buffer), &aliasep) == 0) && aliasep) {
    if (strcmp(aliasep, "myalias") == 0) {
        printf("Alias: %s, Expansion: %s\n", aliasep, resultbuf->alias);
        break;
    }
}

Common Issues

  • EOF: If there are no more aliases to retrieve, getaliasent_r returns an EOF error code.
  • Buffer size: Ensure that the buffer buffer is large enough to hold the alias line.

Integration

getaliasent_r can be combined with other commands to manipulate alias entries:

  • alias: Modify or add aliases.
  • grep: Filter alias entries.
  • sed: Edit alias expansions.

Related Commands

  • getaliasbyname_r
  • alias
  • cat
  • grep