Advanced Bash−Scripting Guide. An in−depth exploration of by Cooper M.

By Cooper M.

This educational assumes no prior wisdom of scripting or programming, yet progresses speedily towards an intermediate/advanced point of guideline ...all the whereas sneaking in little snippets of UNIX knowledge and lore. It serves as a textbook, a guide for self-study, and a reference and resource of data on shell scripting suggestions. The workouts and heavily-commented examples invite lively reader participation, less than the basis that the one solution to quite research scripting is to put in writing scripts.

Show description

Read or Download Advanced Bash−Scripting Guide. An in−depth exploration of the gentle art of shell scripting PDF

Similar electronics: radio books


2-Methoxyestradiol (2ME2) is a byproduct of estrogen metabolism that was once proven to suppress the expansion of speedily dividing endothelial and tumor cells in vitro and in vivo.

Properties of semiconductor alloys: group-IV, III-V and II-VI semiconductors

The most objective of this e-book is to supply a accomplished remedy of the fabrics elements of group-IV, III−V and II−VI semiconductor alloys utilized in a number of digital and optoelectronic units. the themes lined during this booklet comprise the structural, thermal, mechanical, lattice vibronic, digital, optical and provider shipping houses of such semiconductor alloys.

Additional resources for Advanced Bash−Scripting Guide. An in−depth exploration of the gentle art of shell scripting

Example text

Work. echo exit 0 Example 7−6. sh: Testing null strings and unquoted strings, # but not strings and sealing wax, not to mention cabbages and kings... # Using if [ ... ] # If a string has not been initialized, it has no defined value. # This state is called "null" (not the same as zero). if [ −n $string1 ] # $string1 has not been declared or initialized. " fi # Wrong result. # Shows $string1 as not null, although it was not initialized. echo # Lets try it again. if [ −n "$string1" ] # This time, $string1 is quoted.

Bin/bash echo hello echo $? # Exit status 0 returned because command executed successfully. lskdf echo $? # Unrecognized command. # Non−zero exit status returned because command failed to execute. echo exit 113 # Will return 113 to shell. " after script terminates. # By convention, an 'exit 0' indicates success, #+ while a non−zero exit value means an error or anomalous condition. $? is especially useful for testing the result of a command in a script (see Example 12−27 and Example 12−13). , the logical "not" qualifier, reverses the outcome of a test or command, and this affects its exit status.

Fi echo exit 0 The bracket notation for positional parameters leads to a fairly simply way of referencing the last argument passed to a script on the command line. This also requires indirect referencing. args} # Number of args passed. $#} doesn't work. Some scripts can perform different operations, depending on which name they are invoked with. For this to work, the script needs to check $0, the name it was invoked by. There must also exist symbolic links to all the alternate names of the script.

Download PDF sample

Rated 4.02 of 5 – based on 6 votes