shell重定向問(wèn)題

ccnuzxg

1. 
   
2. str1='1 2 3 4'
   
3. str2='2 4'
   
4. 
   
5. echo $(comm -23 <(echo $str1 |xargs -n1|sort) <(echo $str2 |xargs -n1|sort))
   

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當(dāng)使用#!/bin/bash的時(shí)候沒(méi)有問(wèn)題 但是#!/bin/sh的時(shí)候就會(huì)報(bào)錯(cuò)

syntax error near unexpected token `('

難道上面的那種寫(xiě)法不符合postfix規(guī)范嗎？ 如果在#!/bin/sh 該如何寫(xiě)？

seesea2517

回復(fù) 1# ccnuzxg


    是啊，<() 這個(gè)語(yǔ)法是bash特性。用臨時(shí)文件就好了唄。

quote 標(biāo)簽會(huì)解釋出表情來(lái)，看來(lái)還是code標(biāo)簽好啊。

1. Things bash has that sh does not:
   
2.    long invocation options
   
3.    [+-]O invocation option
   
4.    -l invocation option
   
5.    `!' reserved word to invert pipeline return value
   
6.    `time' reserved word to time pipelines and shell builtins
   
7.    the `function' reserved word
   
8.    the `select' compound command and reserved word
   
9.    arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done
   
10.    new ...' and $"..." quoting
    
11.    the $(...) form of command substitution
    
12.    the $(<filename) form of command substitution, equivalent to
    
13.       $(cat filename)
    
14.    the ${#param} parameter value length operator
    
15.    the ${!param} indirect parameter expansion operator
    
16.    the ${!param*} prefix expansion operator
    
17.    the ${param:offset[:length]} parameter substring operator
    
18.    the ${param/pat[/string]} parameter pattern substitution operator
    
19.    expansions to perform substring removal (${p%[%]w}, ${p#[#]w})
    
20.    expansion of positional parameters beyond $9 with ${num}
    
21.    variables: BASH, BASH_VERSION, BASH_VERSINFO, UID, EUID, REPLY,
    
22.          TIMEFORMAT, PPID, PWD, OLDPWD, SHLVL, RANDOM, SECONDS,
    
23.          LINENO, HISTCMD, HOSTTYPE, OSTYPE, MACHTYPE, HOSTNAME,
    
24.          ENV, PS3, PS4, DIRSTACK, PIPESTATUS, HISTSIZE, HISTFILE,
    
25.          HISTFILESIZE, HISTCONTROL, HISTIGNORE, GLOBIGNORE, GROUPS,
    
26.          PROMPT_COMMAND, FCEDIT, FIGNORE, IGNOREEOF, INPUTRC,
    
27.          SHELLOPTS, OPTERR, HOSTFILE, TMOUT, FUNCNAME, histchars,
    
28.          auto_resume
    
29.    DEBUG trap
    
30.    ERR trap
    
31.    variable arrays with new compound assignment syntax
    
32.    redirections: <>, &>, >|, <<<, [n]<&word-, [n]>&word-
    
33.    prompt string special char translation and variable expansion
    
34.    auto-export of variables in initial environment
    
35.    command search finds functions before builtins
    
36.    bash return builtin will exit a file sourced with `.'
    
37.    builtins: cd -/-L/-P, exec -l/-c/-a, echo -e/-E, hash -d/-l/-p/-t.
    
38.         export -n/-f/-p/name=value, pwd -L/-P,
    
39.         read -e/-p/-a/-t/-n/-d/-s/-u,
    
40.         readonly -a/-f/name=value, trap -l, set +o,
    
41.         set -b/-m/-o option/-h/-p/-B/-C/-H/-P,
    
42.         unset -f/-v, ulimit -i/-m/-p/-q/-u/-x,
    
43.         type -a/-p/-t/-f/-P, suspend -f, kill -n,
    
44.         test -o optname/s1 == s2/s1 < s2/s1 > s2/-nt/-ot/-ef/-O/-G/-S
    
45.    bash reads ~/.bashrc for interactive shells, $ENV for non-interactive
    
46.    bash restricted shell mode is more extensive
    
47.    bash allows functions and variables with the same name
    
48.    brace expansion
    
49.    tilde expansion
    
50.    arithmetic expansion with $((...)) and `let' builtin
    
51.    the `[[...]]' extended conditional command
    
52.    process substitution
    
53.    aliases and alias/unalias builtins
    
54.    local variables in functions and `local' builtin
    
55.    readline and command-line editing with programmable completion
    
56.    command history and history/fc builtins
    
57.    csh-like history expansion
    
58.    other new bash builtins: bind, command, compgen, complete, builtin,
    
59.              declare/typeset, dirs, enable, fc, help,
    
60.              history, logout, popd, pushd, disown, shopt,
    
61.              printf
    
62.    exported functions
    
63.    filename generation when using output redirection (command >a*)
    
64.    POSIX.2-style globbing character classes
    
65.    POSIX.2-style globbing equivalence classes
    
66.    POSIX.2-style globbing collating symbols
    
67.    egrep-like extended pattern matching operators
    
68.    case-insensitive pattern matching and globbing
    
69.    variable assignments preceding commands affect only that command,
    
70.       even for builtins and functions
    
71.    posix mode and strict posix conformance
    
72.    redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr,
    
73.       /dev/tcp/host/port, /dev/udp/host/port
    
74.    debugger support, including `caller' builtin and new variables
    
75.    RETURN trap
    
76.    the `+=' assignment operator
    
77. Things sh has that bash does not:
    
78.    uses variable SHACCT to do shell accounting
    
79.    includes `stop' builtin (bash can use alias stop='kill -s STOP')
    
80.    `newgrp' builtin
    
81.    turns on job control if called as `jsh'
    
82.    $TIMEOUT (like bash $TMOUT)
    
83.    `^' is a synonym for `|'
    
84.    new SVR4.2 sh builtins: mldmode, priv
    
85. Implementation differences:
    
86.    redirection to/from compound commands causes sh to create a subshell
    
87.    bash does not allow unbalanced quotes; sh silently inserts them at EOF
    
88.    bash does not mess with signal 11
    
89.    sh sets (euid, egid) to (uid, gid) if -p not supplied and uid < 100
    
90.    bash splits only the results of expansions on IFS, using POSIX.2
    
91.       field splitting rules; sh splits all words on IFS
    
92.    sh does not allow MAILCHECK to be unset (?)
    
93.    sh does not allow traps on SIGALRM or SIGCHLD
    
94.    bash allows multiple option arguments when invoked (e.g. -x -v);
    
95.       sh allows only a single option argument (`sh -x -v' attempts
    
96.       to open a file named `-v', and, on SunOS 4.1.4, dumps core.
    
97.       On Solaris 2.4 and earlier versions, sh goes into an infinite
    
98.       loop.)
    
99.    sh exits a script if any builtin fails; bash exits only if one of
    
100.       the POSIX.2 `special' builtins fails

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ccnuzxg

回復(fù) 2# seesea2517

原來(lái)如此，除了臨時(shí)文件還有沒(méi)有其他簡(jiǎn)單的招數(shù)


   

ly5066113

回復(fù) 3# ccnuzxg


try：

1. echo "$str1 $str2" | sed -r ':a;s/\<(.+)\>(.*)\<\1\>/\2/;ta'

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seesea2517

回復(fù) 3# ccnuzxg


    用bash嘛。。。。想了想沒(méi)別的簡(jiǎn)單方案了……

seesea2517

seesea2517 發(fā)表于 2014-03-28 15:40
回復(fù) 3# ccnuzxg

對(duì)于sh的重定向的辦法而言。

如果為了達(dá)到你腳本語(yǔ)句的功能，則可以這樣（當(dāng)然多個(gè)空格，要不要這么追求完美呢？）：

1. [seesea@UC ~]$ echo "$str1" | tr -d "${str2// }"
   
2. 1  3
   
3. [seesea@UC ~]$ echo "$str1" | sed -r "s/${str2// /|}//g"
   
4. 1  3

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ccnuzxg

回復(fù) 4# ly5066113

多謝，不過(guò)代碼看不懂啊，還有2個(gè)問(wèn)題

剔除的時(shí)候會(huì)多個(gè)空格，還有一種情況，如果str2不在str1中，應(yīng)該是打印出str1 不是str1+str2


   

ccnuzxg

回復(fù) 6# seesea2517

代碼不錯(cuò)，
不過(guò)俺確實(shí)是完美主義，
中間會(huì)多出空格，怎么破

   

seesea2517

回復(fù) 8# ccnuzxg

空格過(guò)濾一下嘍：

1. [seesea@UC ~]$ echo "$str1" | tr -d "${str2// }" | tr -s " "
   
2. 1 3
   
3. [seesea@UC ~]$ echo "$str1" | sed -r "s/${str2// /|}//g; s/ +/ /g"
   
4. 1 3

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ccnuzxg

回復(fù) 9# seesea2517

完美解決了 膜拜。。。