csh,tcsh,bash,sh等shell的区别

2019-09-23 09:42:37于丽

下边是sh有但是bash木有的
        uses variable SHACCT to do shell accounting
        includes `stop' builtin (bash can use alias stop='kill -s STOP')
        `newgrp' builtin
        turns on job control if called as `jsh'
        $TIMEOUT (like bash $TMOUT)
        `^' is a synonym for `|'
        new SVR4.2 sh builtins: mldmode, priv

Implementation differences:
执行情况的不同:
        redirection to/from compound commands causes sh to create a subshell
        bash does not allow unbalanced quotes; sh silently inserts them at EOF
        bash does not mess with signal 11
        sh sets (euid, egid) to (uid, gid) if -p not supplied and uid < 100
        bash splits only the results of expansions on IFS, using POSIX.2
                field splitting rules; sh splits all words on IFS
        sh does not allow MAILCHECK to be unset (?)
        sh does not allow traps on SIGALRM or SIGCHLD
        bash allows multiple option arguments when invoked (e.g. -x -v);
                sh allows only a single option argument (`sh -x -v' attempts
                to open a file named `-v', and, on SunOS 4.1.4, dumps core.
                On Solaris 2.4 and earlier versions, sh goes into an infinite
                loop.)
        sh exits a script if any builtin fails; bash exits only if one of
                the POSIX.2 `special' builtins fails

下边都和上边比较雷同了。。。大致浏览吧。
C2) How does bash differ from the Korn shell, version ksh88?

Things bash has or uses that ksh88 does not:
        long invocation options
        [-+]O invocation option
        -l invocation option
        `!' reserved word
        arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done
        arithmetic in largest machine-supported size (intmax_t)