What is sh? sh (or the Shell Command Language) is a programming language described by the POSIX standard. It has many implementations (ksh88, Dash, …). Bash can also be considered an implementation of sh (see below). Because sh is a specification, not an implementation, /bin/sh is a symlink (or a hard link) to an actual … Read more
Once you grasp that [ is a command, a whole lot becomes clearer! [ is another way to spell “test“. help [ However while they do exactly the same, test turns out to have a more detailed help page. Check help test …for more information. Furthermore note that I’m using, by intention, help test and … Read more
#Getting shell variables into awk may be done in several ways. Some are better than others. This should cover most of them. If you have a comment, please leave below. v1.5 Using -v (The best way, most portable) Use the -v option: (P.S. use a space after -v or it will be less portable. E.g., awk … Read more
In all of the cases above, the variable is correctly set, but not correctly read! The right way is to use double quotes when referencing: echo “$var” This gives the expected value in all the examples given. Always quote variable references! Why? When a variable is unquoted, it will: Undergo field splitting where the value … Read more
In addition to backticks `command`, command substitution can be done with $(command) or “$(command)”, which I find easier to read, and allows for nesting. OUTPUT=$(ls -1) echo “${OUTPUT}” MULTILINE=$(ls \ -1) echo “${MULTILINE}” Quoting (“) does matter to preserve multi-line variable values; it is optional on the right-hand side of an assignment, as word splitting … Read more
Yes. Bash scripts are sensitive to line-endings, both in the script itself and in data it processes. They should have Unix-style line-endings, i.e., each line is terminated with a Line Feed character (decimal 10, hex 0A in ASCII). DOS/Windows line endings in the script With Windows or DOS-style line endings , each line is terminated … Read more
The accepted answer is great. I am making a table that helps in quick comprehension of the topic. The explanation involves a simple variable a as well as an indexed array arr. If we set a=apple # a simple variable arr=(apple) # an indexed array with a single element and then echo the expression in … Read more
EDIT: As OP mentioned in case any de is empty with respective id then print an hyphen, then try following. awk ‘ BEGIN{ OFS=”\t” print “ID\t\tDE” } /ID/{ if(id){ print id,de?de:”-” id=de=”” } id=$2 next } /DE/{ $1=”” sub(/^ +/,””) de=$0 } END{ if(id){ print id,de?de:”-” } }’ Input_file Could you please try following. awk … Read more
Following awk could help you in same. awk ‘{print > NF”column.txt”}’ Input_file Output it will create 3 files named 5column.txt, 4column.txt and 3column.txt.