Unix shell script kit

Unix shell script kit is a collection of utility functions and constants.

The kit works with POSIX shells, including bash, zsh, dash, ksh, sh, etc.

All suggestions are welcome and appreciated.

View source

Download

Download the kit as one file that has everything:

curl -O "https://raw.githubusercontent.com/SixArm/unix-shell-script-kit/main/unix-shell-script-kit"

Source

To use the kit in your own script, you source the kit like this:

. /your/path/here/unix-shell-script-kit

To use the kit in your own script in the same directory, you source the kit like this:

. "$(dirname "$(readlink -f "$0")")/unix-shell-script-kit"

Tracking

• Package: unix-shell-script-kit
• Version: 12.3.0
• Created: 2017-08-22T00:00:00Z
• Updated: 2024-12-10T23:09:11Z
• Website: https://github.com/sixarm/unix-shell-script-kit
• License: GPL-2.0 or GPL-3.0 or contact us for more
• Contact: Joel Parker Henderson ([email protected])

Input/output helpers

out

Print output message to stdout.

out "my message"
STDOUT=> my message

err

Print error message to stderr.

err "my message"
STDERR=> my message

die

Print error message to stderr, then exit with an error code.

die 1 "my message"
STDERR=> my message
=> exit 1

Example with an exit code number and name:

die $EXIT_UNAVAILABLE EXIT_UNAVAILABLE
STDERR=> EXIT_UNAVAILABLE
=> exit 69

Example with more diagnostics:

false || die $? "Fatal error $? on line $LINENO of $0"
STDERR=> Fatal error 1 on line 2 of example.sh"
=> exit 1

big

Print a big banner to stdout, good for human readability.

big "my message"
=>
###
#
# my message
#
###

log

Print a datestamp, unique random id, hostname, process id, and message.

log "my message"
=> 2021-05-04T22:57:54.000000000+00:00 7e7151dc24bd511098ebb248771d8ffb abc.example.com 1234 my message

zid

Generate a 32-bit secure random lowercase hex identifier.

zid
=> 78577554e967951388b5907854b4c337

ask

Prompt the user for a line of input, then return a trimmed string.

ask
=> prompt

utf8

Should the program print UTF-8 characters such as accents and emoji?

This implementation is a heuristic and subject to change as we learn more. This checks the locale charmap. However, it's possible for the charmap to be set to UTF-8, but the terminal is unable to render UTF-8 characters.

utf8
=> true

print_success

Print a success message to stdout, with customization via env vars.

print_success "This is a success message."
=> This is a success message.

The output can be customized by setting:

• PRINT_SUCCESS_START
• PRINT_SUCCESS_STOP

print_warning

Print a warning message to stdout.

print_warning "This is a warning message."
=> This is a warning message.

The output can be customized by setting:

• PRINT_WARNING_START
• PRINT_WARNING_STOP

print_failure

Print a failure message to stdout, with customization via env vars.

print_failure "This is a failure message."
=> This is a failure message.

The output can be customized by setting:

• PRINT_FAILURE_START
• PRINT_FAILURE_STOP

Date & time helpers

now

Get a datetime using our preferred ISO format.

now
=> 2021-05-04T22:59:28.769653000+00:00

Example with a custom datetime:

now -d "2021-01-01"
=> 2021-01-01T00:00:00.000000000+00:00

now_date

Get a date using our preferred ISO format.

now_date
=> 2021-05-04

Example with a custom date, if your date command offers option -d:

now_date -d "January 1, 2021"
=> 2021-01-01

sec

Get the current time in POSIX seconds.

sec
=> 1620169178

age

Get the age of a given time in POSIX seconds.

age 1620169178
=> 19

newer

Is the age of a given time newer than a given number of seconds?

newer 2000000000 && echo "true" || echo "false
=> true

older

Is the age of a given time older than a given number of seconds?

older 1000000000 && echo "true" || echo "false"
=> true

Validation helpers

directory_exists

Does a directory exist?

directory_exists /usr
=> true

directory_exists /loremipsum
=> false

directory_exists_or_die

Ensure a directory exists.

directory_exists_or_die /usr
=> true

directory_exists_or_die /loremipsum
STDERR=> Directory needed: /loremipsum
=> exit $EXIT_IOERR

file_exists

Does a file exist?

file_exists foo.txt
=> true

file_exists loremipsum.txt
=> false

file_exists_or_die

Ensure a file exists.

file_exists_or_die foo.txt
=> true

file_exists_or_die loremipsum.txt
STDERR=> File needed: loremipsum.txt
=> exit $EXIT_IOERR

symlink_exists

Does a symlink exist?

symlink_exists foo.txt
=> true

symlink_exists loremipsum.txt
=> false

symlink_exists_or_die

Ensure a symlink exists.

symlink_exists_or_die foo.txt
=> true

symlink_exists_or_die loremipsum.txt
STDERR=> Symlink needed: loremipsum.txt
=> exit $EXIT_IOERR

command_exists

Does a command exist?

command_exists grep
=> true

command_exists curl
=> false

command_exists_or_die

Ensure a command exists, otherwise die with a help message.

command_exists_or_die grep
=> true

command_exists_or_die loremipsum
STDERR=> Command needed: loremipsum
=> exit 1

command_version_exists_or_die

Ensure a command exists and version is sufficient, otherwise die with a help message.

command_version_exists_or_die grep 1.1 2.2
=> true

command_version_exists_or_die grep 3.3 2.2
STDERR=> Command version needed: grep >= 3.3 (not 2.2)
=> exit 1

var_exists

Does a variable exist?

var_exists HOME
=> true

var_exists FOO
=> false

var_exists_or_die

Ensure a variable exists, otherwise die with a help message.

var_exists_or_die HOME
=> true

var_exists_or_die FOO
STDERR=> Variable needed: FOO
=> exit 1

version

Is a version sufficient?

version 1.1 2.2
=> true

version 3.3 2.2
=> false

version_or_die

Ensure a version is sufficient, otherwise die with a help message.

version_or_die 1.1 2.2
=> true

version_or_die 3.3 2.2
STDERR=> Version needed: >= 3.3 (not 2.2)

Number helpers

int

Convert a number string to an integer number string.

int 1.23
=> 1

sum

Print the sum of numbers.

sum 1 2 3
=> 6

Comparison helpers

cmp_alnums

Compare alnums as groups, such as for word version strings.

cmp_alnums "a.b.c" "a.b.d"
# => -1 (negative one means left < right)

cmp_digits

Compare digits as groups, such as for number version strings.

cmp_digits "1.2.3" "1.2.4"
# => -1 (negative one means left < right)

Extensibility helpers

dot_all

Source all the executable files in a given directory and subdirectories.

dot_all ~/temp
=> . ~/temp/a.sh
=> . ~/temp/b.pl
=> . ~/temp/c.js

run_all

Run all the executable commands in a given directory and subdirectories.

run_all ~/temp
=> ~/temp/a.sh
=> ~/temp/b.pl
=> ~/temp/c.js

sh_all

Shell all the executable commands in a given directory and subdirectories.

sh_all ~/temp
=> sh -c ~/temp/a.sh
=> sh -c ~/temp/b.pl
=> sh -c ~/temp/c.js

rm_all

Remove all files in a given directory and subdirectories-- use with caution.

rm_all ~/temp
=> rm ~/temp/a.sh
=> rm ~/temp/b.pl
=> rm ~/temp/c.js

Text helpers

trim

Remove any space characters at the text's start or finish.

trim "  foo  "
=> foo

slug

Convert a string from any characters to solely lowercase and single internal dash characters.

slug "**Foo** **Goo** **Hoo**"
=> foo-goo-hoo

slugs

Convert a string from any characters to solely lowercase and single internal dash characters and slash characters.

slugs "**Foo** / **Goo** / **Hoo**"
=> foo/goo/hoo

upper_format

Convert text from any lowercase letters to uppercase letters.

upper_format AbCdEf
=> ABCDEF

lower_format

Convert text from any uppercase letters to lowercase letters.

lower_format AbCdEf
=> abcdef

chain_format

Convert a string from any characters to solely alphanumeric and single internal dash characters.

chain_format "**Foo** **Goo** **Hoo**"
=> Foo-Goo-Hoo

snake_format

Convert a string from any characters to solely alphanumeric and single internal underscore characters.

snake_format "**Foo** **Goo** **Hoo**"
=> Foo_Goo_Hoo

space_format

Convert a string from any characters to solely alphanumeric and single internal space characters.

space_format "**Foo** **Goo** **Hoo**"
=> Foo Goo Hoo

touch_format

Convert a string from any characters to solely a command "touch -t" timestamp format.

touch_format "Foo  2021-05-04 22:57:54 Goo"
=> 202105042257.54

select_character_class

Get a string's characters that match a class, with optional offset and length.

Syntax:

select_character_class <string> <class> [offset [length]]

Example with character class:

select_character_class foo123goo456 alpha
=> foogoo

Example with character class and substring offset:

select_character_class foo123goo456 alpha 3
=> goo

Example with character class and substring offset and length:

select_character_class foo123goo456 alpha 3 1
=> g

reject_character_class

Get a string's characters that don't match a class, with optional offset and length.

Syntax:

reject_character_class <string> <class> [offset [length]]

Exapmle with character class:

reject_character_class foo123goo456 alpha
=> 123456

Example with character class and substring offset:

reject_character_class foo123goo456 alpha 3
=> 456

Example with character class and substring offset and length:

reject_character_class foo123goo456 alpha 3 1
=> 4

Random character helpers

random_char

Generate random characters

Syntax:

random_char [characters [length]]

Example:

random_char ABCDEF 8
=> CBACBFDD

Example hexadecimal digit uppercase:

random_char 0-9A-F 8
=> FC56A95C

Example character class for uppercase letters:

random_char '[:upper:]' 8
=> ZMGIQBJB

POSiX character classes for ASCII characters:

Class       Pattern        Description
----------  -------------  -----------
[:upper:]   [A-Z]          uppercase letters
[:lower:]   [a-z]          lowercase letters
[:alpha:]   [A-Za-z]       uppercase letters and lowercase letters
[:alnum:]   [A-Za-z0-9]    uppercase letters and lowercase letters and digits
[:digit:]   [0-9]          digits
[:xdigit:]  [0-9A-Fa-f]    hexadecimal digits
[:punct:]                  punctuation (all graphic characters except letters and digits)
[:blank:]   [ \t]          space and TAB characters only
[:space:]   [ \t\n\r\f\v]  whitespace characters (space, tab, newline, return, feed, vtab)
[:cntrl:]                  control characters
[:graph:]   [^ [:cntrl:]]  graphic characters (all characters which have graphic representation)
[:print:]   [[:graph:] ]   graphic characters and space

random_char_alnum

Get random characters using [:alnum:] class.

random_char_alnum 8
=> 1Yp7M7wc

random_char_alpha

Get random characters using [:alpha:] class.

random_char_alpha 8
=> dDSmQlYD

random_char_blank

Get random characters using [:blank:] class.

random_char_blank 8
=> "  \t  \t  \t"

random_char_cntrl

Get random characters using [:cntrl:] class.

random_char_cntrl 8
=> "^c^m^r^z^a^e^p^u"

random_char_digit

Get random characters using [:digit:] class.

random_char_digit 8
=> 36415110

random_char_graph

Get random characters using [:graph:] class.

random_char_graph 8
=> e'2-3d+9

random_char_lower

random_char_lower 8
=> pgfqrefo

random_char_lower_digit

Get random characters using [:lower:][:digit] classes

random_char_lower_digit 8
=> 69m7o83i

random_char_upper

Get random characters using [:upper:] class.

random_char_upper 8
=> EGXUHNIM

random_char_upper_digit

Get random characters using [:upper:][:digit:] classes

random_char_upper_digit 8
=> L2PT37H6

random_char_print

Get random characters using [:print:] class.

random_char_print 8
=> ),zN87K;

random_char_space

Get random characters using [:space:] class.

random_char_space 8
=> "\n \t\r \v \f"

random_char_xdigit

Get random characters using [:xdigit:] class.

random_char_xdigit 8
=> eC3Ce9eD

Array helpers

array_n

Get the array number of fields a.k.a. length a.k.a. size.

set -- a b c d
array_n "$@"
=> 4

array_i

Get the array item at index i which is 1-based.

set -- a b c d
array_i  "$@" 3
=> c

array_first

Get the array's first item.

set -- a b c d
array_first "$@"
=> a

array_last

Get the array's last item.

set -- a b c d
array_last "$@"
=> d

array_car

Get the array's car item a.k.a. first item.

set -- a b c d
array_car "$@"
=> a

array_cdr

Get the array's cdr items a.k.a. everything after the first item.

set -- a b c d
array_car "$@"
=> b c d

Colors

Colors use ANSI color codes and corresponding variable names:

printf "%sblack\n" $COLOR_BLACK
printf "%sred\n" $COLOR_RED
printf "%sgreen\n" $COLOR_GREEN
printf "%syellow\n" $COLOR_YELLOW
printf "%sblue\n" $COLOR_BLUE
printf "%smagenta\n" $COLOR_MAGENTA
printf "%scyan\n" $COLOR_CYAN
printf "%swhite\n" $COLOR_WHITE
printf "%reset\n" $COLOR_RESET.

The kit will use these colors for standard output and standard error:

STDOUT_COLOR_START="$COLOR_BLUE"
STDOUT_COLOR_STOP="$COLOR_RESET"
STDERR_COLOR_START="$COLOR_RED"
STDERR_COLOR_STOP="$COLOR_RESET"

color

Should the program use color?

The color logic heuristic in order of priority:

1. If NO_COLOR is set to non-empty, then no.
2. If CLICOLOR_FORCE is set to non-empty, then yes.
3. If the TERM is set to "dumb", then no.
4. If the output is on a terminal, then yes.
5. Otherwise, no.

Assert helpers

assert_test

Assert a test utility command succeeds.

assert_test -x program.sh
=> success i.e. no output

assert_test -x notes.txt
STDERR=> assert_test -x notes.txt

assert_empty

Assert an item is empty i.e. null.

assert_empty ""
=> success i.e. no output

assert_empty foo
STDERR=> assert_empty foo

assert_not_empty

Assert an item is not empty i.e. not null.

assert_not_empty foo
=> success i.e. no output

assert_not_empty ""
STDERR=> assert_not_empty

assert_int_eq (eq|ne|ge|gt|le|lt)

Assert an integer comparison.

assert_int_eq 1 1
=> success i.e. no output

assert_int_eq 1 2
STDERR=> assert_int_eq 1 2

There are comparison assertions for integers:

• assert_int_eq is equal to
• assert_int_ne is not equal to
• assert_int_ge is greater than or equal to
• assert_int_gt is greater than
• assert_int_le is less than or equal to
• assert_int_lt is less than

assert_str_eq (eq|ne|ge|gt|le|lt)

Assert a string comparison.

assert_str_eq foo foo
=> success i.e. no output

assert_str_eq foo bar
STDERR=> assert_str_eq foo bar

There are comparison assertions for strings:

• assert_str_eq is equal to
• assert_str_ne is not equal to
• assert_str_ge is greater than or equal to
• assert_str_gt is greater than
• assert_str_le is less than or equal to
• assert_str_lt is less than

assert_str_starts_with

Assert a string starts with a substring.

assert_str_starts_with foobar foo
=> success i.e. no output

assert_str_starts_with foobar xxx
STDERR=> assert_str_starts_with foobar xxx

assert_str_ends_with

Assert a string ends with with a substring.

assert_str_ends_with foobar foo
=> success i.e. no output

assert_str_ends_with foobar xxx
STDERR=> assert_str_ends_with foobar xxx

Make temp helpers

mktemp_dir

Make a temporary directory path.

mktemp_dir
=> /var/folders/4f7b65122b0fb65b0fdad568a65dc97d

mktemp_file

Make a temporary file path.

mktemp_file
=> /var/folders/4f7b65122b0fb65b0fdad568a65dc97d/1d9aafac5373be95d8b4c2dece0b1197

Media helpers

file_media_type

Get a file's media type a.k.a. mime type such as "text/plain".

file_media_type notes.txt
=> text/plain

file_media_type_supertype

Get a file's media type type a.k.a. mime type such as "text".

file_media_type_supertype notes.txt
=> text

file_media_type_subtype

Get a file's media type subtype a.k.a. mime type such as "plain".

file_media_type_subtype notes.txt
=> plain

Font helpers

font_name_exists

Does a font name exist on this system?

font_name_exists Arial
=> true

font_name_exists Foo
=> false

font_name_exists_or_die

Ensure a font name exists, otherwise die with a help message.

font_name_exists_or_die Arial
=> true

font_name_exists_or_die Foo
STDERR=> Font needed: Foo
=> exit 1

Content helpers

file_ends_with_newline

Does a file end with a newline?

file_ends_with_newline notes.txt
=> true

Directory helpers

user_dir

Get a user-specific directory via env var, or XDG setting, or HOME.

user_dir foo
=> $FOO_DIR || $FOO_HOME || $XDG_FOO_DIR || $XDG_FOO_HOME || $HOME/foo

Conventions:

• user_dir bin => binary executable directory
• user_dir cache => cache directory
• user_dir config => configuration directory
• user_dir data => data directory
• user_dir desktop => desktop directory
• user_dir documents => documents directory
• user_dir download => download directory
• user_dir log => logging directory
• user_dir music => music directory
• user_dir pictures => pictures directory
• user_dir publicshare => public share directory
• user_dir runtime => runtime directory
• user_dir state => state directory
• user_dir temp => temporary directory
• user_dir templates => templates directory
• user_dir videos => videos directory

Popular XDG conventions:

• XDG_DESKTOP_DIR => user-specific desktop, such as frequent apps and files.
• XDG_DOCUMENTS_DIR => user-specific documents, such as typical working files.
• XDG_DOWNLOAD_DIR => user-specific downloads, such as internet file downloads.
• XDG_MUSIC_DIR => user-specific music files, such as songs.
• XDG_PICTURES_DIR => user-specific pictures, such as photos.
• XDG_PUBLICSHARE_DIR => user-specific public share, such as file sharing.
• XDG_TEMPLATES_DIR => user-specific templates.
• XDG_VIDEOS_DIR => user-specific videos, such as movies.

POSIX XDG conventions:

• XDG_BIN_HOME => user-specific binaries, analogous to system /usr/bin or $HOME/.local/bin.
• XDG_LOG_HOME => user-specific log files, analogous to system /var/log or $HOME/.local/log.
• XDG_TEMP_HOME => user-specific temporary files, analogous to system /temp or $HOME/.temp.
• XDG_DATA_HOME => user-specific data files, analogous to system /usr/share or $HOME/.local/share.
• XDG_CACHE_HOME => user-specific cache files, analogous to system /var/cache or $HOME/.cache.
• XDG_STATE_HOME => user-specific cache files, analogous to system /var/state or $HOME/.local/state.
• XDG_CONFIG_HOME => user-specific configuration files, analogous to system /etc or $HOME/.config.
• XDG_RUNTIME_HOME => user-specific runtime files such as sockets, named pipes, etc. or $HOME/.runtime.