Basic Shell Scripting

Basics of Shell Scripting#

Shell Script Debugging#

-n, read the commands in the script without executing them, used to check for syntax errors in the script
-v, execute the script while printing the executed script commands to standard error output
-x, provide tracing execution information, printing each executed command and its result sequentially

Sorting an Unordered Column of Numbers in Text with Shell Script#

[root@server ~]# sort -n 190307.txt | awk '{a+=$0;print$0} END {print "sum="a}'

Shell Command to View Line Numbers of Empty Lines in a File#

[root@server ~]# grep -n ^$ filename
[root@server ~]# sed -n '/[a-zA-Z0-9@#$%^&*]!=' filename
[root@server ~]# sed -n '/^$/=' filename
[root@server ~]# awk '/^$/{print NR}' filename

Shell Folder Operations#

Delete all files in a folder but not the folder itself

[root@server-ai ~]# find . -type f | xargs rm -f

Copy only the structure of the directory without copying the contents of the directory

[root@server-ai ~]# find ~ -type d -exec mkdir -p demo/\{\} \;

Find all text files in the current folder that contain the character "math" in their content

[root@server-ai ~]# grep -r "math" /home/chenjiawei/test/shell/ | cut -d ":" -f 1

Traverse all files in the directory and its subdirectories

#! /bin/bash
function read_dir(){
    for file in `ls $1`       # Note that there are two backticks here, indicating a system command
    do
        if [ -d $1"/"$file ]  # Note that there must be a space here, otherwise it will report an error
        then
            read_dir $1"/"$file
        else
            echo $1"/"$file   # Process the file here
        fi
    done
}
# Read the first argument
read_dir $1

Execute the command

$ sh traveDir.sh DIR_NAME