Allows you to enter search strings that include the typical set of characters included in various programming languages.→ Continue reading “Internet Search for Code: SymbolHound”
Category: Programming
Removing the Last Token From a String in Bash with awk
Let’s say that you have some number of files for which you want to create a containing directory that is named with all but the last token of the file name, and you want to remove just the last token to create the name of the directory.
Much easier to explain with an example. Given this list of files:
ls -1
foo_10_10_sometrash
foo_1_sometrash
foo_2_sometrash
foo_3_sometrash
foo_4_sometrash
foo_5_5_sometrash
foo_5_sometrash
foo_6_6_sometrash
foo_7_7_sometrash
foo_8_8_sometrash
foo_9_9_sometrashYou want to create a directory for each → Continue reading “Removing the Last Token From a String in Bash with awk”
Checking that Input or a Variable is an Integer in BASH
Here is a quick snippet for checking whether or not a variable is a valid integer in BASH. It is also a howto for regular expressions in a shell script.
# Make sure that FOO is an integer
if [[ ! "$FOO" =~ ^[0-9]+$ ]]; then
echo "The FOO was NOT an integer"
fiCreating an Array in Bash from a File With Each Element on a Separate Line
Let’s say that you have a file and you would like to convert each line in the file to an element in an array.
The key to this is knowing about and how to manipulate the IFS (Internal Field Separator). The default IFS is whitespace (a space, tab, or newline) and if you create an array passing it a whitespace delimited list of strings, each token will be set to an element in the array.
ARRAY=(a b d Removing The Last N Character From a String in Bash Script with sed
Here is a quick one-liner for trimming a specific number of characters from the end of a string under bash:
# Remove the last 5 characters
$ echo "somestringwith12345" | sed "s/.....$//g"
$ somestringwith
# Remove the last 3 characters
$ echo "somestringwith12345" | sed "s/...$//g"
$ somestringwith12Splitting a String in Bash on the FIRST Occurrence of a Character
About a year ago I posted an article about how to split into an array of values based on a given delimiter in bash.
The following is how to take that same string and split it on the first occurrence of the same user defined delimiter.
Both use the ‘read’ command, but in a slightly different way.
Instead of passing read the -a [aname] parameter which tells it that “The words are assigned to sequential indices of the array → Continue reading “Splitting a String in Bash on the FIRST Occurrence of a Character”
BASH Script With Default Arguments Defined in The Script
Often times you will want to write a BASH script where you don’t want to have to keep track of all of the positional command line arguments and/or you might want to configure it with a set of environmental variables while having a default value for each in the script.
Following is the syntax for declaring them in the shell script, and then an example on how to invoke it.
#!/bin/bash
: ${ARG1:="somedefault_arg1"}
: ${ARG2:="10"}
echo "ARG1 = $ARG1"
echo Count The Number of Characters In a Field With awk
A quick one-liner for counting the number of characters in a given field for each line in an ASCII file.
for i in `cat source.txt`; do echo $i | awk {'print length($1)}' >> counts.txtRunning Dynamically Generated Hive Queries From a Shell Script
If you want to write a HQL hive query and run it mulitple times from a shell script, each time passing it different data for the query, here is a quick example that should get you started.
The first thing to know is that by specifying n number of -hivevar key value pairs when invoking hive on the command line will allow you to pass that data into the hive process.
For example, if you do the following
$ hive Eclipse Android Development Error executing aapt: Cannot run program “/path/to/aapt”: error=2, No such file or directory: error=2, No such file or directory
Even though the ADT bundle provides a 64 bit version, the system requirements indicate that “64-bit distributions must be capable of running 32-bit applications.” I failed to see that when installing it under Fedora Core 20 and was getting the following error from Eclipse:
Error executing aapt: Cannot run program "/home/rchapin/sdks/adt-bundle-linux-x86_64-20131030/sdk/build-tools/android-4.4/aapt": error=2, No such file or directory: error=2, No such file or directory android_sdk line 1 Android ADT ProblemI checked to see if the file was there. Yep. I → Continue reading “Eclipse Android Development Error executing aapt: Cannot run program “/path/to/aapt”: error=2, No such file or directory: error=2, No such file or directory”