The online environment at work has a lot of Perl command-line commands like a sentence, and today concludes some of the things that Perl command line programming.
- e The string followed by the quotation marks is the command to execute:
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king@king:~$ perl-e ' print ' Hello world \ \ n '
Hello World
If you can use multiple-e for more than one command, do you think of sed here? But be aware of which of the middle ";"
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king@king:~$ perl-e ' print ' Hello world \ n '; '-e ' print ' My I-i-perl command line script \ n '
Hello World
My i-Perl command line script
- m import modules to use:
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king@king:~$ perl-mlwp::simple-e ' Print head ' http://www.chinacache.com ', ' \ n '
text/html; charset=utf-81337525116978307200apache/2.2.3 (CentOS)
In addition, M can determine if a module has been installed
- m is similar to-M, except that the-M module name is equivalent to the Use module name, which introduces some of the default functions or other things, and the-M module name closes these defaults, so that you can introduce some of the functions you use only, such as the above example:
Instead of M, there will be no output;-M and-m pass = to introduce a particular function of a module.
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Perl-mcgi= ' header,start_html '-e ' print header, start_html '
- WEquivalent to use warnings
-n-pUse <> to run all @ARGV parameters as files on a per-line basis (with looping meaning oh, often working with other parameters, the file is traversed implicitly by the line. Each row is saved by default in $_, but-p prints the content "duplicate" And-N is more likely to print a line that satisfies a certain condition (here are some useful variables such as $.) Represents the number of rows in the current row):
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king@king:~$ Cat File.txt
A 1
B 2
C 3
king@king:~$ perl-p-E ' print ' file.txt
A 1
A 1
B 2
B 2
C 3
C 3
king@king:~$ perl-n-E ' print ' file.txt
A 1
B 2
C 3
See here is not the thought of SED's-n feature:
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king@king:~$ sed-ne ' P ' file.txt
A 1
B 2
C 3
king@king:~$ sed-e ' P ' file.txt
A 1
A 1
B 2
B 2
C 3
C 3
- I.will be modified to write directly to the file, this and sed is the same oh;
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king@king:~$ Cat File.txt
A 1
B 2
C 3
king@king:~$ perl-pi-e ' s/a/a/' file.txt
king@king:~$ Cat File.txt
A 1
B 2
C 3
-AOpen automatic detach (split) mode. A space is the default separator number. The input is separated according to the separation number and then placed in the default array @F.
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king@king:~$ perl-na-e ' Print $F [1], "\ n" ' file.txt
1
2
3
Is it like awk? There's something more like that. - F, like awk, change the delimiters between fields, by default, by Space and tab;
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king@king:~$ perl-f ': '-alne ' Print $F [0], "", $F [-1] if/bash$/'/etc/passwd
Root/bin/bash
King/bin/bash
Guest-b0siey/bin/bash
See the one on the top. - L's argument? Its main function is to chomp the field and add "\ n" to the end of each output, so that the output can be wrapped; Is it really useful?
Is there any other place like awk? The answer is yes,
begin{},end{} is not also very familiar with it?
Here are some common simple examples
#perl-pi-e ' s/aaa/bbb/' filename modifies files in the current file and does not generate intermediate files. Remember the-i switch because it lets you edit the file in situ.
#perl-ne ' Print if/^aaaaa/' filename filters what is needed in a file like grep. This place uses-N, so one line of action is done until the entire file is read. Also, in the pipeline,-N will be the same to traverse the contents of the pipe.
#perl-N-E ' print ' $. –$_ "' filename in this example, no-ne, just command written-n-e, in fact, this example, is to the current file in the contents of a line number printed out. Note: $. Represents the current line number
#perl-pe ' $_ = ' $. $_ "' filename this is actually the same as above, only use the-p to replace-N, this has a benefit, the same everywhere else, but-p by line to traverse the file, will be printed out to $_.
You remember the awk split domain (awk ' {i = nf–1 print $ + $i} ') Ah, isn't it convenient, let's look at Perl
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#perl-lane ' Print $F [0] + $F [-2] ' This magical place lies in-a, after using-a. Because-n branches are read in, then-a divides the data into @f arrays.
#perl-ne ' Print if/^start$/... /^end$/' Print the place from $start to $end
#perl-ne ' Print if $. >= 15; Exit if $. >= 17; ' Effectively print rows in a range of numbers
#perl-P-i.bak-e ' s/\bfoo\b/bar/g ' *.c the magic of modifying the-I switch in situ is that it replaces the file version produced by the file output with the script for every file in the @ARGV
#perl-ne ' Print scalar reverse $_ ' test to sort the contents of the file in reverse order, such as ABC in the file, it will become the CBA
