Release Notes

busybox-w32 version FRP-4487-gd239d2d52 was released on 2021-10-18. It is the current release. For other release notes see:

• the release before this one
• index of all release notes

Background jobs

The shell in busybox-w32 has always supported the use of background jobs. For example, sleep 10 & runs the sleep applet in the background. This release adds a number of features to improve support for background jobs.

• An interactive shell reports the job id and pid of a newly started job and its completion:

     ~ $ sleep 10 &
     [1] 1888
     ~ $
     [1]+  Done                       sleep 10
     ~ $
  

• The jobs builtin has been enabled. This lets the user see the status of their background jobs:

     ~ $ sleep 100 | sleep 200 &
     [1] 2248
     ~ $ jobs
     [1]+  Running                    sleep 100 | sleep 200
     ~ $ jobs -p
     2248
     ~ $ jobs -l
     [1]+  2248 Running               sleep 100
           3556                       | sleep 200
     ~ $
  

• The kill builtin has been extended to allow jobs to be killed using their job id or the process name:

     ~ $ sleep 100 & sleep 200 & sleep 300 &
     [1] 2532
     [2] 3484
     [3] 2212
     ~ $ jobs
     [3]+  Running                    sleep 300
     [2]-  Running                    sleep 200
     [1]   Running                    sleep 100
     ~ $ kill %-
     [2]-  Terminated                 sleep 200
     ~ $ kill %1
     [1]-  Terminated                 sleep 100
     ~ $ kill %sleep
     [3]+  Terminated                 sleep 300
     ~ $
  

  %% or %+ refer to the current background job, %- is the previous job, %n (where n is a number) is the job with id n, %string is a job whose command begins with string and %?string is a job whose command contains string.
• If the user tries to exit from an interactive shell when some background jobs are still running the shell will prevent them from doing so:

     ~ $ calc &
     [1] 3644
     ~ $ exit
     You have background jobs.
     ~ $
  

  Previously the shell would just hang because the console host refused to shut down while background jobs were still attached. Now the user has the option to terminate the background jobs from the command line or by other means.

Note that this support only extends to background jobs started with the & control operator. busybox-w32 still doesn't support job control using ctrl-z or the fg and bg builtins.

Line endings in vi

The vi text editor in busybox-w32 now supports limited versions of the fileformats and fileformat options from vim. They can be abbreviated to ffs and ff respectively.

When a file is opened for edit vi checks its line endings. If only linefeeds are detected fileformat is set to unix, otherwise it's set to dos. Files are written with line endings appropriate to their fileformat. Thus the format of Unix-style files is preserved.

fileformats defaults to dos,unix but can be changed to unix,dos. This only affects the file type allocated when an empty edit buffer is created.

(GitHub issue #220)

Bug fixes and enhancements

• Device files (such as /dev/null) are now treated as being 'character special' files instead of regular files. This is necessary for the shell to correctly handle /dev/null in conjunction with the noclobber option. (GitHub issue #225)
• The size of the buffer used by the split applet has been increased to provide an improvement in performance. (GitHub issue #224)
• Running a Cygwin/MSYS2 application from the busybox-w32 shell resulted in ANSI escape sequences being broken. This has been fixed. (GitHub issue #223)
• Detection of the use of the Alt key has been made more robust. Previously this could cause problems when using Alt+Tab to cycle between applications. If Alt was released before Tab the code passed a tab character to the application.

Changes imported from upstream

busybox-w32 has been synchronised with upstream BusyBox. As a result the following bug fixes and enhancements are available (among many others):

• The recently-introduced process substitution feature of ash was found to result in this code hanging:

     test() { . /tmp/bb_test; }
     echo "export TEST=foo" >/tmp/bb_test
     test 2>/dev/null
     echo "$TEST"
  

  In addition code of these two forms:

     while true; do cat <(echo hi); done
  
     f() { while true; do cat <(echo hi); done }
     f
  

  leaked file descriptors and eventually failed. Both these flaws have been fixed.
• The shuf applet has been speeded up in cases where the -n option is used to request a limited number of results. For example, this command picks five results from 128 million values:

     shuf -i 1500000000-1628000000 -n 5
  

  In the previous release it took 17 seconds on a test machine. In this release it takes 0.25 seconds. (GitHub issue #212)
• BusyBox ash now supports the bash-like ERR trap. (As a reminder, in busybox-w32 the trap builtin accepts signal names but never handles them. It only handles ERR and EXIT traps.)
• BusyBox ash has improved support for the LINENO variable and adds the FUNCNAME variable. It also now properly respects the ignoreeof option.
• The date and touch applets accept ISO-style dates with a timezone offset. For example, 1999-01-02 03:04:05 +0600 or 1999-01-02 03:04:05Z. (GitHub issue #230)
• The cal applet accepts the -m option to indicate that Monday is the first day of the week. (GitHub issue #231)
• The vi applet now runs initialisation commands from the file .exrc in the user's home directory. Such commands (along with those from the EXINIT environment variable) are processed before the first file is read into memory.
• The --post-file option has been added to the wget applet. (GitHub PR #232)