Yes, the POSIX standard allows this. According to the 2008 version: The here-document shall be treated as a single word that begins after the next <newline> and continues until there is a line containing only the delimiter and a <newline>, with no <blank> characters in between. Then the next here-document starts, if there is one. … Read more
Usage of the $ like ${HOME} gives the value of HOME. Usage of the $ like $(echo foo) means run whatever is inside the parentheses in a subshell and return that as the value. In my example, you would get foo since echo will write foo to standard out
you can for example remove all other chars and count the whats remains, like: var=”text,text,text,text” res=”${var//[^,]}” echo “$res” echo “${#res}” will print ,,, 3 or tr -dc ‘,’ <<<“$var” | awk ‘{ print length; }’ or tr -dc ‘,’ <<<“$var” | wc -c #works, but i don’t like wc.. 😉 or awk -F, ‘{print NF-1}’ … Read more
grep -v -x -f f2 f1 should do the trick. Explanation: -v to select non-matching lines -x to match whole lines only -f f2 to get patterns from f2 One can instead use grep -F or fgrep to match fixed strings from f2 rather than patterns (in case you want remove the lines in a … Read more
You only need a minimal change; single-quote the here-document delimiter after <<. cat <<‘EOF’ >> brightup.sh or equivalently backslash-escape it: cat <<\EOF >>brightup.sh Without quoting, the here document will undergo variable substitution, backticks will be evaluated, etc, like you discovered. If you need to expand some, but not all, values, you need to individually escape … Read more
It’s called a shebang, and tells the parent shell which interpreter should be used to execute the script. #!/bin/sh <——— bourne shell compatible script #!/usr/bin/perl <– perl script #!/usr/bin/php <— php script #!/bin/false <—— do-nothing script, because false returns immediately anyways. Most scripting languages tend to interpret a line starting with # as comment and … Read more
You can set the pipefail shell option option on to get the behavior you want. From the Bash Reference Manual: The exit status of a pipeline is the exit status of the last command in the pipeline, unless the pipefail option is enabled (see The Set Builtin). If pipefail is enabled, the pipeline’s return status … Read more
This will work (tested with zsh and bash): [alias] chs = !git checkout $1 && git status
You can also use parameter expansion: $ filename=foo.txt $ echo “${filename%.*}” foo Just be aware that if there is no file extension, it will look further back for dots, e.g. If the filename only starts with a dot (e.g. .bashrc) it will remove the whole filename. If there’s a dot only in the path (e.g. … Read more
Exporting the function should do it (untested): export -f echo_var seq -f “n%04g” 1 100 | xargs -n 1 -P 10 -I {} bash -c ‘echo_var “$@”‘ _ {} You can use the builtin printf instead of the external seq: printf “n%04g\n” {1..100} | xargs -n 1 -P 10 -I {} bash -c ‘echo_var “$@”‘ … Read more