不知名回忆卷 1

lazy dog appears in typing practice.

local

lcd: local change directory 切换本地目录

execute the command in the local shell

!pwd shows the local working directory

process

signal 9 = SIGKILL, force terminate

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。

object file

.pl

.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

.s is the suffix for an assembly source code file

stderr

libX11.a or libX11.so

vimtutor（原卷记下的就是答案）

recursive

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

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

ESC

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)

perl

Tcl/TK interpreter is wish.

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

Synopsys (第一)

Cadence (第二)

Mentor Graphics (第三) (Siemens 收购)

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

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

Main function: print/concatenate file contents.

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

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

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

Main function: locate command path in PATH.

Syntax: which COMMAND...

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

Syntax: paste [OPTION] FILE...

Main function: convert tabs to spaces.

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

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

Main function: environment variables control program behavior

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

-i, --ignore-environment: Starts with an empty environment

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

EDA = Electronic Design Automation，电子设计自动化（原整理没有写这一项，按 22-23 卷第 20–22 空补上）

CAD = Computer Aided Design，计算机辅助设计（原整理没有写这一项，按 22-23 卷第 23–25 空补上）

Main function: test connectivity and latency.

Syntax: ping [OPTION] DESTINATION

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

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

Syntax: lcd [LOCAL_DIR]

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

Syntax: !COMMAND

• !pwd: local pwd
• !ls: local ls

Main function: print current directory path.

Syntax: pwd [OPTION]

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.

Main function: unmount a filesystem.

Syntax: umount [OPTION] MOUNTPOINT|DEVICE

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

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.