Make sure you understand the three return values of os.walk: for root, subdirs, files in os.walk(rootdir): has the following meaning: root: Current path which is “walked through” subdirs: Files in root of type directory files: Files in root (not in subdirs) of type other than directory And please use os.path.join instead of concatenating with a … Read more
$? is used to find the return value of the last executed command. Try the following in the shell: ls somefile echo $? If somefile exists (regardless whether it is a file or directory), you will get the return value thrown by the ls command, which should be 0 (default “success” return value). If it … Read more
You can use the test construct, [[ ]], along with the regular expression match operator, =~, to check if a string matches a regex pattern (documentation). For your specific case, you can write: [[ “$date” =~ ^[0-9]{8}$ ]] && echo “yes” Or more a accurate test: [[ “$date” =~ ^[0-9]{4}(0[1-9]|1[0-2])(0[1-9]|[1-2][0-9]|3[0-1])$ ]] && echo “yes” # … Read more
Have you tried: eval $cmd For the follow-on question of how to escape * since it has special meaning when it’s naked or in double quoted strings: use single quotes. MYSQL=’mysql AMORE -u username -ppassword -h localhost -e’ QUERY=”SELECT “‘*'” FROM amoreconfig” ;# <– “double”‘single'”double” eval $MYSQL “‘$QUERY'” Bonus: It also reads nice: eval mysql … Read more
Windows type command works similarly to UNIX cat. Example 1: type file1 file2 > file3 is equivalent of: cat file1 file2 > file3 Example 2: type *.vcf > all_in_one.vcf This command will merge all the vcards into one.
The following sends standard output to the null device (bit bucket). scriptname >/dev/null And if you also want error messages to be sent there, use one of (the first may not work in all shells): scriptname &>/dev/null scriptname >/dev/null 2>&1 scriptname >/dev/null 2>/dev/null And, if you want to record the messages, but not see them, … Read more
The raiserror method raiserror(‘Oh no a fatal error’, 20, -1) with log This will terminate the connection, thereby stopping the rest of the script from running. Note that both severity level 20 or higher and the WITH LOG option are necessary for it to work this way. This even works with GO statements, eg. print … Read more
Scripting languages are programming languages that don’t require an explicit compilation step. For example, in the normal case, you have to compile a C program before you can run it. But in the normal case, you don’t have to compile a JavaScript program before you run it. So JavaScript is sometimes called a “scripting” language. … Read more
set -x enables a mode of the shell where all executed commands are printed to the terminal. In your case it’s clearly used for debugging, which is a typical use case for set -x: printing every command as it is executed may help you to visualize the control flow of the script if it is … Read more
The following bash code will pass $file to command where $file will represent every file in /dir for file in /dir/* do cmd [option] “$file” >> results.out done Example el@defiant ~/foo $ touch foo.txt bar.txt baz.txt el@defiant ~/foo $ for i in *.txt; do echo “hello $i”; done hello bar.txt hello baz.txt hello foo.txt