fexecve - Linux
Overview
fexecve
is a Linux utility that executes a program in a separate process while inheriting the file descriptors of the parent process. It is primarily used to execute programs that communicate with the parent process through file descriptors, such as pipes, sockets, or terminals.
Syntax
fexecve [-a] [-e env-file] [-f file-descriptor] program [arguments...]
Options/Flags
- -a: Append the environment variables from
env-file
to the existing environment. - -e env-file: Read environment variables from
env-file
and add them to the environment. - -f file-descriptor: Specify the file descriptor to use for program input. Defaults to standard input (0).
Examples
Simple execution: Execute program
using the parent process’s file descriptors.
fexecve program arg1 arg2
Pass environment variables: Execute program
with environment variables defined in env-file
.
fexecve -e env-file program arg1 arg2
Specify input file descriptor: Execute program
using file descriptor 3 for input.
fexecve -f 3 program arg1 arg2
Execute a script: Execute the script test.sh
while inheriting the parent process’s file descriptors.
fexecve test.sh
Common Issues
- Permission denied: Ensure that the specified program has execute permissions.
- File descriptor not available: Verify that the specified file descriptor is valid.
- Stale file descriptors: If the parent process closes a file descriptor before the child process uses it,
fexecve
will fail.
Integration
fexecve
can be integrated with other commands to perform advanced tasks:
- Pipe output from a program using
pipe
:
program | fexecve child-program args...
- Redirect child process output to a file using
>
:
fexecve program args... > output.txt
Related Commands
execve
: Similar tofexecve
but doesn’t inherit file descriptors.pipe
: Creates a pipe for communication between processes.socketpair
: Creates a pair of connected sockets.