[Bash shell] Find something in some files

Command “find” is one of the most powerful command in linux, here is an exmaple that allows list the files which contain something.

find . -name \*.[type of your files] -exec grep -q "[text that you want to search]" "{}" \; -print

For example, I have two shell files in my folder :

$ ll
drwxrwxr-x 3 bo bo 4096 juin 13 14:56 ./
drwxr-xr-x 16 bo bo 4096 juin 13 14:04 ../
-rwxrwxrwx 1 bo bo 2554 juin 12 18:05 first.sh*
-rwxrwxrwx 1 bo bo 1283 juin 12 16:10 second.sh*

And I want to find the string “spark” in these files

$ find . -name \*.sh -exec grep -q "spark" "{}" \; -print

And I got :


[Bash shell] Display the output with color

In bash shell, we have multiple ways to display the output, but do u know how to do this with color ?
Like this :
Image 8

It’s not so hard to do, the only thing we need to understand is  : ANSI escape code

An example of correspondence between the code and the color :

Black        0;30     Dark Gray     1;30
Red          0;31     Light Red     1;31
Green        0;32     Light Green   1;32
Brown/Orange 0;33     Yellow        1;33
Blue         0;34     Light Blue    1;34
Purple       0;35     Light Purple  1;35
Cyan         0;36     Light Cyan    1;36
Light Gray   0;37     White         1;37

The example in bash shell


NC='\033[0m' 		# No color
RED='\033[0;31m'	# red
PURPLE='\033[0;35m'	# purple

printf "My ${PURPLE}name${NC} is ${RED}BO${NC} \n"

Do this in shell, and launch your script, you will get the same from the image in the beginning of this article.

[SHELL] if syntax

Shell if
[ -a FILE ] 如果 FILE 存在则为真。
[ -b FILE ] 如果 FILE 存在且是一个块特殊文件则为真。
[ -c FILE ] 如果 FILE 存在且是一个字特殊文件则为真。
[ -d FILE ] 如果 FILE 存在且是一个目录则为真。
[ -e FILE ] 如果 FILE 存在则为真。
[ -f FILE ] 如果 FILE 存在且是一个普通文件则为真。
[ -g FILE ] 如果 FILE 存在且已经设置了SGID则为真。
[ -h FILE ] 如果 FILE 存在且是一个符号连接则为真。
[ -k FILE ] 如果 FILE 存在且已经设置了粘制位则为真。
[ -p FILE ] 如果 FILE 存在且是一个名字管道(F如果O)则为真。
[ -r FILE ] 如果 FILE 存在且是可读的则为真。
[ -s FILE ] 如果 FILE 存在且大小不为0则为真。
[ -t FD ] 如果文件描述符 FD 打开且指向一个终端则为真。
[ -u FILE ] 如果 FILE 存在且设置了SUID (set user ID)则为真。
[ -w FILE ] 如果 FILE 如果 FILE 存在且是可写的则为真。
[ -x FILE ] 如果 FILE 存在且是可执行的则为真。
[ -O FILE ] 如果 FILE 存在且属有效用户ID则为真。
[ -G FILE ] 如果 FILE 存在且属有效用户组则为真。
[ -L FILE ] 如果 FILE 存在且是一个符号连接则为真。
[ -N FILE ] 如果 FILE 存在 and has been mod如果ied since it was last read则为真。
[ -S FILE ] 如果 FILE 存在且是一个套接字则为真。
[ FILE1 -nt FILE2 ] 如果 FILE1 has been changed more recently than FILE2, or 如果 FILE1 exists and FILE2 does not则为真。
[ FILE1 -ot FILE2 ] 如果 FILE1 比 FILE2 要老, 或者 FILE2 存在且 FILE1 不存在则为真。
[ FILE1 -ef FILE2 ] 如果 FILE1 和 FILE2 指向相同的设备和节点号则为真。
[ -o OPTIONNAME ] 如果 shell选项 “OPTIONNAME” 开启则为真。
[ -z STRING ] “STRING” 的长度为零则为真。
[ -n STRING ] or [ STRING ] “STRING” 的长度为非零 non-zero则为真。
[ STRING1 == STRING2 ] 如果2个字符串相同。 “=” may be used instead of “==” for strict POSIX compliance则为真。
[ STRING1 != STRING2 ] 如果字符串不相等则为真。
[ STRING1 < STRING2 ] 如果 “STRING1” sorts before “STRING2” lexicographically in the current locale则为真。
[ STRING1 > STRING2 ] 如果 “STRING1” sorts after “STRING2” lexicographically in the current locale则为真。
[ ARG1 OP ARG2 ] “OP” is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than, less than or equal to, greater than, or greater than or equal to “ARG2”, respectively. “ARG1” and “ARG2” are integers.

Shell in Unix

A shell is software that provides an interface for users of an operating system which provides access to the services of a kernel. — Wikipedia

I share the note of shell training here. In the training, we’ve used Bash for the most of the time.

I picked up two images from Internet, it describes how does shell works.



There are two families of shell:
1. Bourne shell(sh) 1978, Korn shell (ksh) 1983, Bourne again shell (bash) 1989, Z shell (zsh)
2. C shell (csh), Turbo C shell (tcsh) (Tenex Tops shell/Toronto shell)

Prompt(after that we type our commands):

shell user

Function of a shell

shell function

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