Bit of awk should do it? awk ‘{s+=$1} END {print s}’ mydatafile Note: some versions of awk have some odd behaviours if you are going to be adding anything exceeding 2^31 (2147483647). See comments for more background. One suggestion is to use printf rather than print: awk ‘{s+=$1} END {printf “%.0f”, s}’ mydatafile
In cross-platform, lowest-common-denominator sh you use: #!/bin/sh value=`cat config.txt` echo “$value” In bash or zsh, to read a whole file into a variable without invoking cat: #!/bin/bash value=$(<config.txt) echo “$value” Invoking cat in bash or zsh to slurp a file would be considered a Useless Use of Cat. Note that it is not necessary to … Read more
Here is a bash-only parser that leverages sed and awk to parse simple yaml files: function parse_yaml { local prefix=$2 local s=”[[:space:]]*” w='[a-zA-Z0-9_]*’ fs=$(echo @|tr @ ‘\034’) sed -ne “s|^\($s\):|\1|” \ -e “s|^\($s\)\($w\)$s:$s[\”‘]\(.*\)[\”‘]$s\$|\1$fs\2$fs\3|p” \ -e “s|^\($s\)\($w\)$s:$s\(.*\)$s\$|\1$fs\2$fs\3|p” $1 | awk -F$fs ‘{ indent = length($1)/2; vname[indent] = $2; for (i in vname) {if (i > indent) … Read more
Just to reiterate what has been posted for other shells, in Bash the following works: alias blah=”function _blah(){ echo “First: $1”; echo “Second: $2″; };_blah” Running the following: blah one two Gives the output below: First: one Second: two
Run your script with . . myscript.sh This will run the script in the current shell environment. export governs which variables will be available to new processes, so if you say FOO=1 export BAR=2 ./runScript.sh then $BAR will be available in the environment of runScript.sh, but $FOO will not.
The shebang line has never been specified as part of POSIX, SUS, LSB or any other specification. AFAIK, it hasn’t even been properly documented. There is a rough consensus about what it does: take everything between the ! and the \n and exec it. The assumption is that everything between the ! and the \n … Read more
Using wait() or waitpid() It is not possible on Unix and derivatives using POSIX functions like wait() and waitpid(). The exit status information returned consists of two 8-bit fields, one containing the exit status, and the other containing information about the cause of death (0 implying orderly exit under program control, other values indicating that … Read more
For Bash scripts, the most direct and performant approach is: if compgen -G “${PROJECT_DIR}/*.png” > /dev/null; then echo “pattern exists!” fi This will work very speedily even in directories with millions of files and does not involve a new subshell. Source The simplest should be to rely on ls return value (it returns non-zero when … Read more
You need to use the -F option: -F/–form <name=content> Specify HTTP multipart POST data (H) Try this: curl \ -F “userid=1” \ -F “filecomment=This is an image file” \ -F “image=@/home/user1/Desktop/test.jpg” \ localhost/uploader.php
When the shell sees > index.html in the command line it opens the file index.html for writing, wiping off all its previous contents. To fix this you need to pass the -i option to sed to make the changes inline and create a backup of the original file before it does the changes in-place: sed … Read more