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List of Examples
Bash completion extends bashs standard completion behavior to achieve complex command lines with just a few keystrokes. This project was conceived to produce programmable completion routines for the most common Linux/UNIX commands, reducing the amount of typing sysadmins and programmers need to do on a daily basis.
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configure completion will return the entire option
string (e.g. --this-option=DESCRIPTION) so one can see what kind of data
is required and then simply delete the descriptive text and add one’s own
data. If unset or null (default), configure completion will strip
everything after the = when returning completions.
cvs commit completion will try to complete on
remotely checked-out files. This requires passwordless access to the
remote repository. Default is unset.
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This document attempts to explain the basic styles and patterns that are used in the bash completion. New code should try to conform to these standards so that it is as easy to maintain as existing code. Of course every rule has an exception, but it’s important to know the rules nonetheless!
This is particularly directed at people new to the bash completion codebase, who are in the process of getting their code reviewed. Before getting a review, please read over this document and make sure your code conforms to the recommendations here.
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The bash-completion package contains an automated test suite. Running the tests should help verifying that bash-completion works as expected. The tests are also very helpful in uncovering software regressions at an early stage.
The bash-completion test suite is written on top of the DejaGnu testing framework. DejaGnu is written in Expect, which in turn uses Tcl — Tool command language.
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Installing DejaGnu should be easy using your local package manager.
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The tests are grouped into different areas, called tool in DejaGnu:
Each tool has a slightly different way of loading the test fixtures, see Test context below.
The tests are run by calling runtest in the test directory:
runtest --outdir log --tool completion runtest --outdir log --tool install runtest --outdir log --tool unit
The commands above are already wrapped up in shell scripts within the test directory:
./runCompletion ./runInstall ./runUnit
Let’s consider this real-life example where an ssh completion bug is fixed. First you’re triggered by unsuccessful tests:
$ ./runCompletion
...
=== completion Summary ===
# of expected passes 283
# of unexpected failures 8
# of unresolved testcases 2
# of unsupported tests 47Take a look in log/completion.log to find out which specific command is failing.
$ vi log/completion.log
Search for UNRESOLVED or FAIL. From there scroll up to see which .exp test is failing:
/@Running ./completion/ssh.exp ... ... UNRESOLVED: Tab should complete ssh known-hosts at prompt
In this case it appears ssh.exp is causing the problem. Isolate the ssh tests by specifying just ssh.exp to run. Furthermore add the --debug flag, so output gets logged in dbg.log:
$ ./runCompletion ssh.exp --debug
...
=== completion Summary ===
# of expected passes 1
# of unresolved testcases 1Now we can have a detailed look in dbg.log to find out what’s going wrong. Open dbg.log and search for UNRESOLVED (or FAIL if that’s what you’re looking for):
UNRESOLVED: Tab should complete ssh known-hosts at prompt
From there, search up for the first line saying:
expect: does "..." match regular expression "..."
This tells you where the actual output differs from the expected output. In this case it looks like the test "ssh -F fixtures/ssh/config <TAB>" is expecting just hostnames, whereas the actual completion is containing commands - but no hostnames. So what should be expected after "ssh -F fixtures/ssh/config <TAB>" are both commands and hostnames. This means both the test and the completion need fixing. Let’s start with the test.
$ vi lib/completions/ssh.exp
Search for the test "Tab should complete ssh known-hosts". Here you could’ve seen that what was expected were hostnames ($hosts):
set expected "^$cmd\r\n$hosts\r\n/@$cmd$"
Adding all commands (which could well be over 2000) to expected, seems a bit overdone so we’re gonna change things here. Lets expect the unit test for _known_hosts assures all hosts are returned. Then all we need to do here is expect one host and one command, just to be kind of sure that both hosts and commands are completed.
Looking in the fixture for ssh:
$ vi fixtures/ssh/known_hosts
it looks like we can add an additional host ls_known_host. Now if we would perform the test "ssh -F fixtures/ssh/config ls<TAB>" both the command ls and the host ls_known_host should come up. Let’s modify the test so:
$ vi lib/completions/ssh.exp ... set expected "^$cmd\r\n.*ls.*ls_known_host.*\r\n/@$cmd$"
Running the test reveals we still have an unresolved test:
$ ./runCompletion ssh.exp --debug
...
=== completion Summary ===
# of expected passes 1
# of unresolved testcases 1But if now look into the log file ‘dbg.log` we can see the completion only returns commands starting with ls but fails to match our regular expression which also expects the hostname `ls_known_host’:
$ vi dbg.log ... expect: does "ssh -F fixtures/ssh/config ls\r\nls lsattr lsb_release lshal lshw lsmod lsof lspci lspcmcia lspgpot lss16toppm\r\nlsusb\r\n/@ssh -F fixtures/ssh/config ls" (spawn_id exp9) match regular expression "^ssh -F fixtures/ssh/config ls\r\n.*ls.*ls_known_host.*\r\n/@ssh -F fixtures/ssh/config ls$"? no
Now let’s fix ssh completion:
$ vi ../contrib/ssh ...
until the test shows:
$ ./runCompletion ssh.exp
...
=== completion Summary ===
# of expected passes 2Now let’s consider a unit test failure. First you’re triggered by unsuccessful tests:
$ ./runUnit
...
=== unit Summary ===
# of expected passes 1
# of unexpected failures 1Take a look in log/unit.log to find out which specific command is failing.
$ vi log/unit.log
Search for UNRESOLVED or FAIL. From there scroll up to see which .exp test is failing:
/@Running ./unit/_known_hosts_real.exp ... ... FAIL: Environment should stay clean
In this case it appears _known_hosts_real.exp is causing the problem. Isolate the _known_hosts_real test by specifying just _known_hosts_real.exp to run. Furthermore add the --debug flag, so output gets logged in dbg.log:
$ ./runUnit _known_hosts_real.exp --debug
...
=== completion Summary ===
# of expected passes 1
# of unexpected failures 1Now, if we haven’t already figured out the problem, we can have a detailed look in dbg.log to find out what’s going wrong. Open dbg.log and search for UNRESOLVED (or FAIL if that’s what you’re looking for):
FAIL: Environment should stay clean
From there, search up for the first line saying:
expect: does "..." match regular expression "..."
This tells you where the actual output differs from the expected output. In this case it looks like the the function _known_hosts_real is unexpectedly modifying global variables cur and flag. In case you need to modify the test:
$ vi lib/unit/_known_hosts_real.exp
The primary Wikipedia page is called test suite and not testsuite, so that’s what this document sticks to.
The name and location of this code generation script come from Ruby on Rails' script/generate.
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The test environment needs to be put to fixed states when testing. For instance the bash prompt (PS1) is set to the current test directory, followed by an ampersand (@). The default settings for bash reside in config/bashrc and config/inputrc.
For each tool (completion, install, unit) a slightly different context is in effect.
When the completions are tested, invoking DejaGnu will result in a call to completion_start() which in turn will start bash --rcfile config/bashrc.
Example 9.1. What happens when completion tests are run?
| runtest --tool completion
V
+----------+-----------+
| lib/completion.exp |
| lib/library.exp |
| config/default.exp |
+----------+-----------+
:
V
+----------+-----------+ +---------------+ +----------------+
| completion_start() +<---+ config/bashrc +<---| config/inputrc |
| (lib/completion.exp) | +---------------+ +----------------+
+----------+-----------+
| ,+----------------------------+
| ,--+-+ "Actual completion tests" |
V / +------------------------------+
+----------+-----------+ +-----------------------+
| completion/*.exp +<---| lib/completions/*.exp |
+----------+-----------+ +-----------------------+
| \ ,+--------------------------------+
| `----------------------+-+ "Completion invocation tests" |
V +----------------------------------+
+----------+-----------+
| completion_exit() |
| (lib/completion.exp) |
+----------------------+Setting up bash once within completion_start() has the speed advantage that bash - and bash-completion - need only initialize once when testing multiple completions, e.g.:
runtest --tool completion alias.exp cd.exp
Example 9.2. What happens when install tests are run?
| runtest --tool install
V
+----+----+
| DejaGnu |
+----+----+
|
V
+------------+---------------+
| (file: config/default.exp) |
+------------+---------------+
|
V
+------------+------------+
| (file: lib/install.exp) |
+-------------------------+This is the bash configuration file (bashrc) used for testing:
# -*- mode: shell-script; sh-basic-offset: 8; indent-tabs-mode: t -*-
# ex: ts=8 sw=8 noet filetype=sh
#
# bashrc file for DejaGnu testsuite
# Use emacs key bindings
set -o emacs
# Use bash strict mode
set -o posix
# Unset `command_not_found_handle' as defined on Debian/Ubuntu, because this
# troubles and slows down testing
unset -f command_not_found_handle
# Set prompt to ignore current root directory; display path starting
# from here. E.g. prompt: /fixtures/@
TESTDIR=$(pwd)
export PS1='$(wd=$(pwd); echo ${wd#$TESTDIR}/)@'
export PS2='> '
# Configure readline
export INPUTRC=$TESTDIR/config/inputrc
# Ensure enough columns so expect doesn't have to care about line breaks
stty columns 150
# Make sure default settings are in effect
unset -v \
COMP_CONFIGURE_HINTS \
COMP_CVS_REMOTE \
COMP_KNOWN_HOSTS_WITH_HOSTFILE \
COMP_TAR_INTERNAL_PATHS
# Load bash testsuite helper functions
. lib/library.shThis is the readline configuration file (inputrc) used for testing:
# -*- mode: shell-script; sh-basic-offset: 8; indent-tabs-mode: t -*-
# ex: ts=8 sw=8 noet filetype=sh
#
# Readline init file for DejaGnu testsuite
# See: info readline
# Press TAB once (instead of twice) to auto-complete
set show-all-if-ambiguous on
# No bell. No ^G in output
set bell-style none
# Don't query user about viewing the number of possible completions
set completion-query-items -1
# Display completions sorted horizontally, not vertically
set print-completions-horizontally on
# Don't use pager when showing completions
set page-completions off