bash fails to redirect standard output of a pipeline to the input file of the fist pipeline's command
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| bash (Ubuntu) |
New
|
Undecided
|
Unassigned | ||
Bug Description
In a non-interactive bash session, redirecting the standard output to the file read by the pipeline's first command leads to random resuts : the redirection sometimes works, but generally the file is overwriten by an empty file.
In an interactive session, the redirection works, which leads the user to look somewhere else to find a bug.
However, when the last command is a user-writen function which simulates "cat", the resulting file is correct, as in an interactive session.
Bash documentation does not prohibit such processing.
Arbiel
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: bash 4.3-7ubuntu1.5
ProcVersionSign
Uname: Linux 3.13.0-106-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.23
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Dec 12 23:51:22 2017
InstallationDate: Installed on 2014-05-30 (1292 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
LANGUAGE=fr_FR
PATH=(custom, no user)
XDG_RUNTIME_
LANG=fr_FR.UTF-8
SHELL=/bin/bash
SourcePackage: bash
UpgradeStatus: No upgrade log present (probably fresh install)
| Arbiel Perlacremaz (arbiel-perlacremaz) wrote | #1 |
| Arbiel Perlacremaz (arbiel-perlacremaz) wrote | #2 |
Don't consider this as a bash bug. It's a misunderstanding by myself of the pipeline operation.
Maybe a comment should be included in the reference manual to cleary explain that the last command may try to open for writing the file still open for reading by the first command, and that such a situation obviously fails.