多个进度条

Question

除了我之前关于 shell 脚本中的多线程的查询之外，我很好奇是否可以有多个进度条。

这是我预期结果的代码片段：

Output : 1 of 100  Files Completed   # Thread1
Output : 10 of 45 files Completed     # Thread 2    

这些行已更新，显示进度。可以在shell中实现吗？

Answer 1

如果您的子进程输出是可过滤的，那么您可以将每个子进程的标准输出重定向到不同的文件描述符，然后调用一个函数来循环该文件描述符的输出。然后您可以尝试使用 printf 来更新进度表。但这就是你会遇到麻烦的地方。不确定 Bash 的内置 printf 是否可以处理终端的细节。我从未尝试过在 Bash 中编写一个进行多行输出的进度表。为什么不使用对话框？

Answer 2

是的，这很有可能。

假设您现有的代码（基于您之前的帖子）当前是这样的：

do_something() {
  ...
  echo -ne "\r$index of $No_of_Files Completed"
  ...
}

do_something A &
do_something B &
do_something C &
wait

...那么您可以执行以下调整以实现您想要的效果：

# Background tasks will no longer write directly to the console; instead, 
#  they will write to temporary files which will be read periodically 
#  by a special log printer task (which will display everything nicely.) 
# 
# Name of temporary files 
STATUS_BASENAME="/tmp/~$.status" 
# Process IDs of backgrounded tasks; we record them so we can wait on them 
#  specifically but not wait on the special log printer task 
TASK_PIDS="" 

do_something() { 
  # First parameter must be a task ID starting at 0 incremented by 1 
  TASK_ID=$1 ; shift 
  ...
  # We write new status to status file (note we don't echo -n, we want that 
  #  trailing newline) 
  # Try to go through a temporary status file which we rename afterwards to 
  #  avoid race conditions with the special log printer task 
  echo "$x of 5 Completed" >"${STATUS_BASENAME}.${TASK_ID}.tmp" 
  mv "${STATUS_BASENAME}.${TASK_ID}.tmp" "${STATUS_BASENAME}.${TASK_ID}" 
  ...
} 

# Special log printer task 
status_printer() { 
  # First time in the loop is special insofar we don't have to 
  #  scroll up to overwrite previous output. 
  FIRST_TIME=1 
  while true ; do 
    # If not first time, scroll up as many lines as we have 
    #  regular background tasks to overwrite previous output. 
    test $FIRST_TIME -eq 0 && for PID in $TASK_PIDS ; do 
      echo -ne '\033M' # scrol up one line using ANSI/VT100 cursor control sequences 
    done 
    FIRST_TIME=0
    TASK_ID=0
    for PID in $TASK_PIDS ; do 
      # If status file exists print first line 
      test -f "${STATUS_BASENAME}.${TASK_ID}" && head -1 "${STATUS_BASENAME}.${TASK_ID}" || echo "waiting..." 
      TASK_ID=`expr $TASK_ID + 1` # using expr for portability :) 
    done 
    test -f "${STATUS_BASENAME}.done" && return
    sleep 1 # seconds to wait between updates 
  done 
} 

do_something 0 A &
 TASK_PIDS="$TASK_PIDS $!" 
do_something 1 B & 
 TASK_PIDS="$TASK_PIDS $!" 
do_something 2 C &
 TASK_PIDS="$TASK_PIDS $!" 

status_printer & 
  PRINTER_PID=$! 

# Wait for background tasks 
wait $TASK_PIDS 

# Stop special printer task instead of doing just
#  kill $PRINTER_PID >/dev/null
touch "${STATUS_BASENAME}.done"
wait $PRINTER_PID

# Cleanup 
rm -f "${STATUS_BASENAME}."* 

Answer 3

就像 pv -c 所做的那样？

当然，请参阅 src/pv/cursor.c 。虽然仅通过 shell 并不真正安全，但一个小型 C 实用程序可以处理它。