不知名回忆卷 1

这套题目不全，而且和前面的题目重复性高

选择

lazy dog appears in typing practice.
l in lcd means local

lcd: local change directory 切换本地目录

! in !pwd means execute the command in the local shell

!pwd shows the local working directory

kill -9 3721 means sending #9 signal to a process with PID of 3721

signal 9 = SIGKILL, force terminate

@ages indicates this variable is of type: array

in Perl, @ = array（数组）; $ = scalar（标量）; % = hash.（哈希）
哈希（hash）在 Perl 里指的是一种键值对（key-value pairs）数据结构，也叫关联数组或字典/map。

.o is for : object file
Perl suffix: .pl
Python suffix: .py

Suffix Naming Convention
.sh/.bash/.csh #Shell Script
.c/.cpp/ /.h/.hpp #C/C++ Source/Header File
.py #Python Script
.java #Java Source File
.o #Object File，gcc -c之后生成的目标文件
.s #Assembly Source File，汇编文件
.a #Library (static)，静态库
.so #Dynamic-linking Library (shared object)，动态库
.f #Fortran Source File
.pl #Perl Script perl 脚本
.tcl #TCL/TK Script

.sis the suffix for an assembly source code file
demo_inout.c prints out 'stdout' and stderr
-lX11 means the needed library should be a file called libX11.a or libX11.so.
vimtutor is a program running tutorial for vim
-r means recursive

这个题目没给全，-r 大概有 reverse recusive read 等几种

$@ means this rule’s current target

$@ 目标文件，即 $(TARGET)
$^ 表示所有的依赖文件，即 file1.o file2.o file3.o
$< 表示第一个依赖文件，即 file1.o
$? 表示比目标还要新的依赖文件列表
$* 当前任务的基名，即不包括后缀

Press ESC key to return command mode in vi.
In s/../../, s means substitution

和前面几个卷子的一样，分析结果
将改行的第一个 Oct. 换成 Nov.。注意，这里将 . 视为普通的点，所以文本匹配的是 Oct. 而不是 Oct

use more to display the content of some files, one key to exit = q

空格（space）下翻一页，b（back）返回一页，q（quit）退出(类似man)

Interpreter program of Perl scripts: perl

Tcl/TK interpreter is wish.

A Class-B IP address: 135.0.1.1

注意最开始的数字大小
Class A：以 0 开头 1–126
Class B：以 10 开头 128–191
Class C：以 110 开头 192–223
Class D：以 1110 开头 224–239
Class E：以 1111 开头 240–255

填空

最大的EDA公司？

Synopsys (第一)

Cadence (第二)

Mentor Graphics (第三) (Siemens 收购)

如何熟练使用 perl / shell / tcl / C/C++，从多个角度回答。

Core syntax: variables, if/loop, functions, arrays/maps, I/O

Typical tasks:

Shell = automation
Perl = text/regex
Tcl = tool/EDA scripting
C/C++ = performance/core logic

Toolchain: run/env, compile/link, debug, errors

Engineering habits: args check, help, logs, clean structure

Mini project: use them together (Shell control + Tcl run tool + Perl parse + C/C++ compute)

常用语法：变量、条件循环、函数、数组/哈希、读写文件
典型用途：
Shell=自动化
Perl=文本/正则
Tcl=工具/EDA脚本
C/C++=性能/核心模块
工具链：运行环境、编译链接、调试、排错
工程习惯：参数检查、help、日志、结构清晰
小项目整合：Shell控流程 + Tcl跑工具 + Perl解析 + C/C++计算

Meta chararcter 背吧，没招了

大题

chmod

Main function: change file/directory permissions (r/w/x for u/g/o).

Syntax: chmod [OPTION] MODE FILE... / chmod [OPTION] OCTAL FILE...

u+x: add execute permission to the user(owner). e.g., chmod u+x a.sh
755: set perms to rwxr-xr-x. e.g., chmod 755 a.sh

cat

Main function: print/concatenate file contents.

Syntax: cat [OPTION] [FILE]...

-n: number all output lines. e.g., cat -n a.txt

cp

Main function: copy files/directories.

Syntax: cp [OPTION] source_file target_file

-r: copy directories recursively. e.g., cp -r DIR DEST
-f: Overwrite an existing destination file without prompting (without requiring --force).
-i: interactive, prompt before overwrite
-r: copy directories recursively

which

Main function: locate command path in PATH.

Syntax: which COMMAND...

pwd

Main function: print current directory path.

Syntax: pwd [OPTION]

du

Main function: estimate file space usage.

Syntax: du [OPTION]... [FILE]...

-s: summary only (total).

-h: human-readable units.

du -sh DIR: total size of DIR in human-readable form.

--max-depth=1: show only 1 level of subdirectories.

du -h --max-depth=1 DIR: sizes of first-level entries in DIR.

paste

Main function: merge lines of files side-by-side.

Syntax: paste [OPTION] FILE...

expand

Main function: convert tabs to spaces.

Syntax: expand [OPTION] [FILE]...

-t: have tabs N characters apart, not 8, e.gexpand -t 4 a.txt

env

Main function: environment variables control program behavior

Syntax: env [OPTION] [NAME=VALUE]... [COMMAND [ARG]...]

-i, --ignore-environmentStarts with an empty environment

-u NAME, --unset=NAME: Removes (unsets) the environment variable NAME for the command being run.

umount

Main function: unmount a filesystem.

Syntax: umount [OPTION] MOUNTPOINT|DEVICE

umount /mnt/usb: unmount the filesystem mounted on /mnt/usb.

tar

Main function: archive files (create/list/extract), optionally gzip.

Syntax: tar [options] {directory | file}…

Key options:

-c: create archive
-t: list archive contents
-x: extract archive
-f ARCHIVE: archive file name to read/write
-z: gzip compress/decompress (.tar.gz)

Examples:
tar -cf a.tar FILE...: create a tar archive.
tar -tf a.tar: list contents.
tar -xf a.tar: extract.
tar -czf a.tar.gz FILE...: create gzip-compressed archive.
tar -xzf a.tar.gz: extract gzip-compressed archive.

ping

Main function: test connectivity and latency.

Syntax: ping [OPTION] DESTINATION

-c 4: send 4 packets then stop (count).

lcd

Main function: change the local directory to an FTP client.

Syntax: lcd [LOCAL_DIR]

!pwd

Main function: in FTP, ! runs a local shell command; !pwd shows the local directory.

Syntax: !COMMAND

!pwd: local pwd
!ls: local ls

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