Posts Tagged ‘command line’

If you’re using a linux terminal and need to convert all upper case characters to lowercase, there are a number of ways you can do it. One of the easiest is to use tr: tr ‘[:upper:]’ ‘[:lower:]’ For example: $ echo “HeLlo WOrlD” | tr ‘[:upper:]’ ‘[:lower:]’ hello world :upper: and :lower: can be reversed […]

Awk is a useful language for many command line tasks. Often awk is used on the command line on its own or with strings piped to it, but it is possible to turn that awk code into an executable script. Consider the following script. This file contains awk code with a shebang of awk -f. […]

Removing Git Tags

Posted: 26th March 2015 by Tim in Git
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If you’ve accidentally added a git tag, or if you want to remove old tags, these tags can be removed with the following three commands: git tag -d <my_tag> git push origin :<my_tag> git push –tags For example, if you want to remove the tag bad_tag, you would use these commands: git tag -d bad_tag […]

With Docker, you can specify the command to run inside the container on the command line. But what if you want to run multiple commands? You can’t escape the && syntax, or wrap the command in quotes, as Docker won’t recognise it. The trick here is to use sh -c ‘<command1 && command2 [&& command3 […]

If you have a HyperSQL (HSQL) database stored in a file, it is often useful to be able to query that database from the command line. This can be done using the following command: hsqldb-sqltool –inlineRc url=jdbc:hsqldb:file:<db_name>,user=<username>,password=[<password>] By default, user SA with no password will exist for each database file. If the database does not […]

If you have a JAR file and want to print the details from MANIFEST.MF, this can be done with one command in linux, using the unzip utility. For example: $ unzip -p /usr/share/java/hsqldb.jar META-INF/MANIFEST.MF Manifest-Version: 1.0 Created-By: 1.7.0_03-b147 (Oracle Corporation) Specification-Title: HSQLDB Implementation-Title: Standard runtime Class-Path: /usr/share/java/servlet-api-3.0.jar Main-Class: org.hsqldb.util.SqlTool Ant-Version: Apache Ant 1.8.2 Implementation-Vendor: buildd […]

Command Line Arguments in Bash

Posted: 14th June 2014 by Tim in Bash, Linux
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In Bash, arguments passed in on the command line are stored in numbered variables. For example, the first argument is $1, the second argument is $2, and so on. The total number of arguments passed to the program is stored in $# $0 contains the path to the program. This path may be an absolute […]

Sed is a useful tool for editing strings on the command line. Changing characters to uppercase or lowercase can be done easily with this tool by simply adding one or more of the following to your substitution string: * \L – convert all proceeding characters to lowercase * \U – convert all proceeding characters to […]

The learning curve for LaTeX documents can be a steep one. This step-by-step guide covers installing and setting up the LaTeX environment, and creating and compiling your first document so that you can read and distribute it. Setting up the LaTeX environment A few things need to be installed before we can start creating documents. […]