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This Bash script updates its first argument by replacing it with “5” while keeping the rest unchanged. "${@:2}"<\/code> in the set command denotes all arguments except the first one. Finally, the script accesses the special variable $@<\/code> to show all the command line arguments including the modified first argument.<\/p>\n<\/div><\/div>![\"Changing](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2024\/02\/4.-Changing-the-first-argument-in-Bash.png\")
Running the script with arguments \u201cNull\u201d, 7 and 13 changes the first argument \u201cNull\u201d to 5.<\/p>\n
<\/span>5. How to Skip the First Argument in Bash Script<\/span><\/h3>\nSometimes users want to get rid of the first argument passed to a Bash script. To skip the first argument, use the shift <\/strong>command to shift all the positional parameters to the left by one. Here’s how you can do it:<\/p>\n#!\/bin\/bash\n\n# Skip the first argument\nshift\n\n# Now $1 refers to the second argument\necho "Second argument: $1"\n\n# Loop through all remaining arguments\necho "Remaining arguments: $@"<\/code><\/pre>\n EXPLANATION<\/div>
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The script uses shift <\/strong>to skip the first positional argument passed to the script. Therefore, the second positional argument becomes the first argument and can be accessed using $1<\/code>. Finally, it also prints all the arguments using $@<\/code>, which represents all arguments passed to the script except the first one, as the first one has been shifted out.<\/p>\n<\/div><\/div>![\"Skipping](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2024\/02\/5.-Skipping-the-first-argument-in-Bash.png\")
Here, the script is executed with arguments 4,5 and 6. Due to the use of shift<\/strong>, all the arguments are shifted to the left by one position. As a result, the second argument becomes accessible by the first positional parameter ($1). Therefore, $@<\/strong> prints 5 and 6 effectively skipping the first argument(4) provided to the script.<\/p>\n<\/span>Conclusion<\/span><\/h2>\nIn conclusion, handling the first argument in Bash script is quite easy once you are familiar with the idea of positional parameters. The first positional parameter ($1) is used to access the first argument passed to a script. Moreover, the set<\/strong> built-in and shift<\/strong> command allows users to change or skip the first argument of a Bash script. I hope this article has helped you manipulate the first argument of your script.<\/p>\n<\/span>People Also Ask<\/span><\/h2>\n<\/span>How to check if the first argument is empty?<\/span><\/h3>\nTo check whether the first argument is empty or not use the operators such -n<\/strong> or -z<\/strong> with the test<\/strong> command in an if statement. if [ -n "$1" ]<\/code> holds true if the length of the first argument is nonzero. On the other hand,\u00a0 if [ -z "$1" ]<\/code> is true if the length of the first argument is 0.<\/p>\n<\/span>What is the difference between $1 and $@?<\/span><\/h3>\nThough both $1 and $@ are used to represent command line arguments, they don\u2019t refer to the same set of arguments. $1 is used to access the first positional parameter whereas $@ expands to all the command line arguments. One can say, “$@” is equivalent to “$1” “$2” “$3″…up to the last argument.<\/p>\n
<\/span>How to store the first argument in a variable in Bash script?<\/span><\/h3>\nAssign $1 as the value of a variable to store the first argument in a variable within a Bash script. For instance:<\/p>\n
#!\/bin\/bash\n\n# Store the first argument in a variable\narg1=$1<\/code><\/pre>\nHere, variable arg1<\/strong> contains the value of the first argument provided to the script.<\/p>\n<\/span>Why is $1 in a function not printing the script’s first argument?<\/span><\/h3>\n$1 in a function can\u2019t print a script\u2019s first argument. Arguments provided to a script are accessible using positional parameters only within the main level of the script not in a function body written in the script. A function can take its own set of arguments independent of the parent script containing the function. So, a function written in a script can access arguments that are provided to the function while calling the function within the script.<\/p>\n