if (expr )command如果指定的表达式的计算结果为 true,则会执行带参数的单个 command。command 上的变量替换会提前进行,并同时对 if 命令的其余部分执行此操作。command 必须是一个简单命令,不能是管道、命令列表或带括号的命令列表。注:当command 未执行时,即使 expr 为false,也会发生 I/O 重定向(这是一个...
1.if / then / else if (expr) thencommandselse if (expr2) thencommandselsecommandsendifExample:#!/bin/cshif ($#argv == 0) thenecho "No number to classify"else if ($#argv > 0) thenset number = $argv[1]if ($number < 0) then@ class = 0else if (0 <= $number && $number <...
foreach、switch、while、if . . . then、および else の各組み込みコマンドは、入力行の最初のワードとして記述しなければなりません。 もし、シェルの入力が見つからないのにループが読み込まれているときは、その入力はバッファリングされます。シェルは、ループによって示される再読...
if( $?VAR )then echo"VAR exists" if($VAR==true)then echo"VAR is true" endif endif # I want something more like this: if(( $?VAR ) && ($VAR==true))then echo"VAR exists and is true" endif 看答案 短路评估是其中之一c shell的很多东西都没有...
whenever a remote system uses theexeccommand on a command sent by the local system, both the command and the shell are carried out. For example,exec csh rcp -tFilenameexecutes the.cshrcfile and treats the echoed output as the expected response. Anifclause can be used to check for the$pro...
Looping is prevented if the first word of the new text is the same as the old by flagging it to prevent further aliasing. Other loops are detected and cause an error. Note that the mechanism allows aliases to introduce parser metasyntax. For example, alias ms 'man \!* | manstrip' ...
In the Bourne shell, you can open or dup random file descriptors. For example exec 2>errs.out means that from then on, stderr goes into errs file. Or what if you just want to throw away stderr and leave stdout alone? Pretty simple operation, eh?
[能源化工]比泽尔CSH系列半封闭整体式螺杆压缩机应用手册 1SH-170-3-CN 应用手册 Applications Manual Semi-hermetic Compact Screws CSH65 .. CSH95 SH-170-3-CN 半封闭整体式螺杆压缩机CSH65 .. CSH95
If the !ref is omitted or is not a valid range, functions are free to treat the sheet as empty or attempt to guess the range. The standard utilities that ship with this library treat sheets as empty (for example, the CSV output is an empty string). When reading a worksheet with the...
"Running the Spack executable directly (for example, invoking", color.colorize("@*c{For bash/zsh/sh:}"), "./bin/spack) will bypass the shell function and print this", " . %s/setup-env.sh" % spack.paths.share_path, "placeholder message, even if...