格式化过长的行

可以直接使用 fmt 命令，或者使用下面的脚本，借助了 nroff 命令

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
#!/bin/bash
# fmt: used to format text lines
# -w width 指定宽度
# -h 是否启用连字符

while getopts "hw:" opt; do
    case "${opt}" in
    h) hype=1 ;;
    w) width="$OPTARG" ;;
    *) echo "ignore unknow argument: $opt" ;;
    esac
done

shift $(($OPTIND - 1))

nroff <<EOF
.ll ${width:-72} # set up default value
.na
.hy ${hype:-0}
.pl 1
$(cat "$@")
EOF

exit 0

显示目录内容

脚本的作用在于打印出目录下的文件块大小（每个块 1024 字节）或目录下的条目个数。

在打印出所有的内容前，为了使得输出的每行展示两列, 并进行对齐，使用了如下的步骤：

  1. 使用了 sed 流文本编辑器命令，先将原始输出的两行变为一行，再将可能包含的空格字符先替换为 \0 null 字符（具体的过程见后面的注释）
  2. 使用 awk 命令格式化输出

sed 命令真是一个非常有趣的命令！

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
#!/usr/bin/env bash

if [[ $# -gt 1 ]]; then
    echo "Usage: $0 [dirname]"
    exit 1
elif [[ $# -eq 1 ]]; then
    cd "$@"
    # if cd command failed because it is not a valid path
    if [[ $? -ne 0 ]]; then
        exit 1
    fi
fi

# shell will extend '*' as all files and directories under the current directory
for file in *; do
    if [[ -d "$file" ]]; then
        size=$(ls "$file" | wc -l | sed 's/[^[:digit:]]//g')
        echo "$file ($size entr(y|ies))"
    else
        size=$(ls -sk $file | awk '{print $1}')
        echo "$file (${size}KB)"
    fi
done | \
sed -n \
-e '$!N' \
-E -e 's/\n/\x0/g' \
-e 'p' | \
awk -F "\0" '{ printf "%-39s %-39s\n",$1,$2 }' 

### a bettern output fotmat

## step 1: use sed to make things easy and right
# -n			disable automatic priting
# '$!N' 		append the next line of input into the pattern space, now we have two lines in sed's pattern space
# 's/\n/\x0/g'	replace '\n' in pattern space, so we make two lines a line separated by '\0'
# 'p'			print the content of pattern space

### step 2: awk final output
# make the '\0' as field delimiter, and format the output

测试结果：

1
2
3
4
5
6
7
8
9
10
11
12
13
guo@DESKTOP-4L69AND:/mnt/e/learning-dir/shell-learning/scripts$ sudo ./formatDir.sh /
bin (171 entr(y|ies))                   boot (0 entr(y|ies))
dev (210 entr(y|ies))                   dump-new.rdb (8KB)
etc (189 entr(y|ies))                   home (1 entr(y|ies))
init (620KB)                            lib (22 entr(y|ies))
lib64 (1 entr(y|ies))                   media (0 entr(y|ies))
mnt (8 entr(y|ies))                     opt (6 entr(y|ies))
proc (46 entr(y|ies))                   root (0 entr(y|ies))
run (11 entr(y|ies))                    sbin (220 entr(y|ies))
snap (0 entr(y|ies))                    srv (0 entr(y|ies))
sys (10 entr(y|ies))                    tmp (79 entr(y|ies))
usr (8 entr(y|ies))                     var (13 entr(y|ies))
zookeeper_server.pid (0KB)

提醒工具

添加提醒

1
2
3
4
5
6
7
8
9
10
11
12
13
#!/usr/bin/env bash
# 简单的命令行提醒工具

remindFile="$HOME/.remind"

if [ $# -eq 0 ]; then
    echo "enter note and end with ctrl-D:" # ctrl-D Terminate input, or exit shell 终止输入或退出 shell
    cat - >>$remindFile
else
    echo "$@" >>$remindFile
fi

exit 0

查询提醒

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
#!/usr/bin/env bash
# remindMe 查看提醒

remindFile="$HOME/.remind"

if [ ! -f $remindFile ]; then
    echo "$0: You don't have a .remind file under your user home" >/dev/stderr
    exit 1
fi

if [ $# -eq 0 ]; then
    more $remindFile
else
    grep -i -- "$@" $remindFile | ${PAGER:-more} # 变量为空默认赋值，即使用 more 命令来展示内容；-- 将后面参数不再作为 grep 命令的参数来解析，出于安全执行命令考虑
fi

exit 0

交互式包装器

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
#!/usr/bin/env bash
# frontBc 交互式计算器，这里我只是为了参考源代码的编写方式，即如何实现一个简单的交互式包装器、

function show_help() {
    cat <<EOF
This is a help documentation, supported commands are as follows:
    (1) del del an item
    (2) add add a new item
    (3) mov move a item
EOF
}

echo "enter 'help' for help, 'quit' to quit"
echo -n "calc> "

while read command args; do
    case $command in
    quit | exit | bye) exit 0 ;;
    help | ?) show_help ;;
    *) echo "$command $args" ;;
    esac
    echo -n "calc> "
done

echo ""
exit 0