SHELL中如何获得管道前面的命令的返回值？

xuphys

SHELL中如何获得管道前面的命令的返回值？
bash中可以用PIPESTATUS，但是其他的shell呢？
谢谢。

南极雨

好像其他的shell也都支持这个pip吧...
windows下的powershell 用的不多，不太清楚！

xuphys

powershell貌似不行，不过我不关心。我想知道其他的UNIX shell是否支持呢？

xuphys

ksh好像就没有。。。

cjaizss

其他shell没有很正常

ly5066113

1. comp.unix.shell FAQ(转载http://home.comcast.net/~j.p.h/)
   
2. 11. How do I get the exit code of cmd1 in cmd1|cmd2
   
3. 
   
4.     First, note that cmd1 exit code could be non-zero and still don't
   
5.     mean an error. This happens for instance in
   
6. 
   
7.     cmd | head -1
   
8. 
   
9.     you might observe a 141 (or 269 with ksh93) exit status of cmd1,
   
10.     but it's because cmd was interrupted by a SIGPIPE signal when
    
11.     "head -1" terminated after having read one line.
    
12. 
    
13.     To know the exit status of the elements of a pipeline
    
14.     cmd1 | cmd2 | cmd3
    
15. 
    
16.     a. with zsh:
    
17. 
    
18.        The exit codes are provided in the pipestatus special array.
    
19.        cmd1 exit code is in $pipestatus[1], cmd3 exit code in
    
20.        $pipestatus[3], so that $? is always the same as
    
21.        $pipestatus[-1].
    
22. 
    
23.     b. with bash:
    
24. 
    
25.        The exit codes are provided in the PIPESTATUS special array.
    
26.        cmd1 exit code is in ${PIPESTATUS[0]}, cmd3 exit code in
    
27.        ${PIPESTATUS[2]}, so that $? is always the same as
    
28.        ${PIPESTATUS: -1}.
    
29. 
    
30.     c. with any other Bourne like shells
    
31. 
    
32.        You need to use a trick to pass the exit codes to the main
    
33.        shell.  You can do it using a pipe(2). Instead of running
    
34.        "cmd1", you run "cmd1; echo $?" and make sure $? makes it way
    
35.        to the shell.
    
36. 
    
37.        exec 3>&1
    
38.        eval `
    
39.          # now, inside the `...`, fd4 goes to the pipe
    
40.          # whose other end is read and passed to eval;
    
41.          # fd1 is the normal standard output preserved
    
42.          # the line before with exec 3>&1
    
43.          exec 4>&1 >&3 3>&-
    
44.          {
    
45.            cmd1 4>&-; echo "ec1=$?;" >&4
    
46.          } | {
    
47.            cmd2 4>&-; echo "ec2=$?;" >&4
    
48.          } | cmd3
    
49.          echo "ec3=$?;" >&4
    
50.        `
    
51. 
    
52.     d. with a POSIX shell
    
53. 
    
54.        You can use this function to make it easier:
    
55. 
    
56.        run() {
    
57.          j=1
    
58.          while eval "\${pipestatus_$j+:} false"; do
    
59.            unset pipestatus_$j
    
60.            j=$(($j+1))
    
61.          done
    
62.          j=1 com= k=1 l=
    
63.          for a; do
    
64.            if [ "x$a" = 'x|' ]; then
    
65.              com="$com { $l "'3>&-
    
66.                          echo "pipestatus_'$j'=$?" >&3
    
67.                        } 4>&- |'
    
68.              j=$(($j+1)) l=
    
69.            else
    
70.              l="$l \"\$$k\""
    
71.            fi
    
72.            k=$(($k+1))
    
73.          done
    
74.          com="$com $l"' 3>&- >&4 4>&-
    
75.                     echo "pipestatus_'$j'=$?"'
    
76.          exec 4>&1
    
77.          eval "$(exec 3>&1; eval "$com")"
    
78.          exec 4>&-
    
79.          j=1
    
80.          while eval "\${pipestatus_$j+:} false"; do
    
81.            eval "[ \$pipestatus_$j -eq 0 ]" || return 1
    
82.            j=$(($j+1))
    
83.          done
    
84.          return 0
    
85.        }
    
86.       
    
87.        use it as:
    
88.       
    
89.        run cmd1 \| cmd2 \| cmd3
    
90.        exit codes are in $pipestatus_1, $pipestatus_2, $pipestatus_3

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cjaizss

ly5066113 发表于 2011-01-25 13:14

    呵呵,办法总是人想的

xuphys

似乎只能用很麻烦的的方法了