Linux tr command All In One

Linux tr command All In One

tr 转义或删除字符

tr

$ man tr > man-tr.md

$ cat man-tr.md

TR(1)                                             User Commands                                            TR(1)

NAME
       tr - translate or delete characters

SYNOPSIS
       tr [OPTION]... SET1 [SET2]

DESCRIPTION
       Translate, squeeze, and/or delete characters from standard input, writing to standard output.

       -c, -C, --complement
              use the complement of SET1

       -d, --delete
              delete characters in SET1, do not translate

       -s, --squeeze-repeats
              replace  each  sequence  of  a repeated character that is listed in the last specified SET, with a
              single occurrence of that character

       -t, --truncate-set1
              first truncate SET1 to length of SET2

       --help display this help and exit

       --version
              output version information and exit

       SETs are specified as strings of characters.  Most represent themselves.  Interpreted sequences are:

       \NNN   character with octal value NNN (1 to 3 octal digits)

       \\     backslash

       \a     audible BEL

       \b     backspace

       \f     form feed

       \n     new line

       \r     return

       \t     horizontal tab

       \v     vertical tab

       CHAR1-CHAR2
              all characters from CHAR1 to CHAR2 in ascending order

       [CHAR*]
              in SET2, copies of CHAR until length of SET1

       [CHAR*REPEAT]
              REPEAT copies of CHAR, REPEAT octal if starting with 0

       [:alnum:]
              all letters and digits

       [:alpha:]
              all letters

       [:blank:]
              all horizontal whitespace

       [:cntrl:]
              all control characters

       [:digit:]
              all digits

       [:graph:]
              all printable characters, not including space

       [:lower:]
              all lower case letters

       [:print:]
              all printable characters, including space

       [:punct:]
              all punctuation characters

       [:space:]
              all horizontal or vertical whitespace

       [:upper:]
              all upper case letters

       [:xdigit:]
              all hexadecimal digits

       [=CHAR=]
              all characters which are equivalent to CHAR

       Translation occurs if -d is not given and both SET1 and SET2 appear.  -t may be used only when  translat‐
       ing.  SET2 is extended to length of SET1 by repeating its last character as necessary.  Excess characters
       of SET2 are ignored.  Only [:lower:] and [:upper:] are guaranteed to expand in ascending order;  used  in
       SET2  while  translating,  they  may  only be used in pairs to specify case conversion.  -s uses the last
       specified SET, and occurs after translation or deletion.

AUTHOR
       Written by Jim Meyering.

REPORTING BUGS
       GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
       Report any translation bugs to <https://translationproject.org/team/>

COPYRIGHT
       Copyright  ©  2020  Free  Software  Foundation,  Inc.   License  GPLv3+:  GNU  GPL  version  3  or  later
       <https://gnu.org/licenses/gpl.html>.
       This  is  free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent
       permitted by law.

SEE ALSO
       Full documentation <https://www.gnu.org/software/coreutils/tr>
       or available locally via: info '(coreutils) tr invocation'

GNU coreutils 8.32                               September 2020                                            TR(1)
pi@raspberrypi:~/Desktop/man-docs $ 

demos

pdf crawler / pdf 爬虫 / shell script 爬虫

#!/bin/bash 绝对路径 ⚠️

#!/usr/bin/env bash 相对路径 ✅

#!/usr/bin/env bash

# 下载目录
downdir="/Users/xgqfrms-mbp/Documents/swift-ui/Memorize/000-xyz/pdfs/"

# $1 是传递给 shell 的第一个参数
# read line 按行读取文件
cat $1 | while read line
do
  # shell 变量需要使用双引号包裹， 或 echo $line
  echo "$line"
  cd $downdir
  str=$line
  # 按行分割，每行一个, 正则表达式：字符串转数组
  array=(${str//;/ })
  echo "$array"
  url=${array[0]}
  # tr 删除换行字符 ✅
  filename=$(echo ${array[1]} | tr -d '\r')
  # filename=$(echo "l" + ${index} + ".pdf" | tr -d '\r')
  # filename=$(echo "l${index}.pdf" | tr -d '\r')
  # cURL 执行下载, -o 输出文件
  curl $url -o $filename
done

# exit 0

# mkdir pdfs
$ bash ./auto-download-pdfs.sh cs193p.txt
# OR, 可执行脚本
$ chmod +x ./auto-download-pdfs.sh
$ ./auto-download-pdfs.sh cs193p.txt

Stanford CS193p

cs193p.txt

https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l1.pdf;l1.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l2.pdf;l2.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l3.pdf;l3.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l4.pdf;l4.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l5.pdf;l5.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l6.pdf;l6.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l7.pdf;l7.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l8.pdf;l8.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l9.pdf;l9.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l10.pdf;l10.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l11.pdf;l11.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l12.pdf;l12.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l13.pdf;l12.pdf
https://cs193p.sites.stanford.edu/sites/g/files/sbiybj16636/files/media/file/l14.pdf;l14.pdf

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refs

Linux bash shell script 批量下载文件 All In One

https://www.cnblogs.com/xgqfrms/p/16073509.html

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