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 anEOF
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