Snippets

Логин

Feature Group

bash internal (293)

bash

This demonstrates directory navigation using cd - to toggle between the current and previous directories.


pwd # /home/user/foo
cd bar/
pwd # /home/user/foo/bar
cd -
pwd # /home/user/foo

bash internal file and stream operations directory operations directory navigation

bash

This demonstrates printing the current working directory using the pwd command.

pwd

bash internal file and stream operations directory navigation print working directory

bash

This demonstrates declaring a variable as an integer type and incrementing its value by 1 in Bash.


declare -i count  # Declare as type integer
count+=1          # Increment

bash internal data manipulations other variable features variable types (integer)

bash

This demonstrates how to unset (delete) a variable in Bash.


unset foo

bash internal data manipulations other variable features variable unset

bash

This demonstrates using the IFS variable to split a comma-separated string and iterate over its elements in a for loop.


IFS=','

string="apple,banana,cherry"
for fruit in $string; do
    echo "Fruit: $fruit"
done

bash internal data manipulations string manipulation and expansions IFS (Internal Field Separator)

bash

This demonstrates the use of an inline if-else statement to check if the current user is rehan and print yes or no accordingly.


[[ $USER = 'rehan' ]] && echo 'yes' || echo 'no'

bash internal flow control tests (conditions)inline if-else

bash

This demonstrates printing the current Bash process ID using the $BASHPID variable.


echo "Current Bash PID: $BASHPID"

bash internal data manipulations other variable features process ID

bash

This demonstrates accessing all command-line arguments in a Bash script.


echo "All arguments: $@"

bash internal data manipulations positional arguments positional argument

bash

This demonstrates the use of built-in Bash variables to access script information like return values, process ID, and arguments.


echo "Last program's return value: $?"
echo "Script's PID: $$"
echo "Number of arguments passed to script: $#"
echo "All arguments passed to script: $@"
echo "Script's arguments separated into different variables: $1 $2..."

bash internal data manipulations positional arguments built-in variables

bash

This demonstrates redirecting both standard output and standard error to a single log file in Bash.


python hello.py > "output-and-error.log" 2>&1
# redirect both output and errors to output-and-error.log
# &1 means file descriptor 1 (stdout), so 2>&1 redirects stderr (2) to the current
# destination of stdout (1), which has been redirected to output-and-error.log.

bash internal file and stream operations stream redirection and piping combined redirection

bash

This demonstrates printing the current user's username using the built-in $USER variable.


echo "Current user: $USER"

bash internal data manipulations environment variables built-in environment variables

bash

This demonstrates the use of an integer variable and a conditional while loop in Bash to decrement and print values.


declare -i counter
counter=10
while [ $counter -gt 2 ]; do
  echo The counter is $counter
  counter=counter-1
done

bash internal loops while loop conditional

bash

This demonstrates the use of a subshell to isolate directory changes, ensuring the main shell's working directory remains unchanged.


(cd somedir; echo "I'm now in $PWD")
pwd # still in first directory

bash internal process management subshell execution

bash

This demonstrates three different for loop examples in Bash, including iterating over a numerical range, a predefined list of filenames, and all files in the current directory, showcasing various file manipulation techniques.


for i in {0..10..2}
  do
    echo "Index: $i"
  done

for filename in file1 file2 file3
  do
    echo "Content: " >> $filename
  done

for filename in *;
  do
    echo "Content: " >> $filename
  done

bash internal loops for loop numerical range iteration

bash

This demonstrates removing the longest matching suffix from a string using parameter expansion.


${FOO%%suffix}

bash internal data manipulations string manipulation and expansions parameter expansion suffix removal

bash

This demonstrates various methods of redirecting stdout and stderr in Bash, including appending, discarding, and combining streams.


python hello.py > output.txt            # stdout to (file)
python hello.py >> output.txt           # stdout to (file), append
python hello.py 2> error.log            # stderr to (file)
python hello.py 2>&1                    # stderr to stdout
python hello.py 2>/dev/null             # stderr to (null)
python hello.py >output.txt 2>&1        # stdout and stderr to (file), equivalent to &>
python hello.py &>/dev/null             # stdout and stderr to (null)
echo "$0: warning: too many users" >&2  # print diagnostic message to stderr

bash internal file and stream operations stream redirection and piping stdout redirection

bash

This demonstrates the use of a case statement to evaluate user input for weather conditions and print corresponding messages.


echo "What's the weather like tomorrow?"
read weather

case $weather in
  sunny | warm ) echo "Nice weather: " $weather
  ;;
  cloudy | cool ) echo "Not bad weather: " $weather
  ;;
  rainy | cold ) echo "Terrible weather: " $weather
  ;;
  * ) echo "Don't understand"
  ;;
esac

bash internal flow control tests (conditions)case statement

bash

This demonstrates basic array manipulation in Bash, including accessing elements, counting, slicing, and iterating.


array=(one two three four five six)
# Print the first element:
echo "${array[0]}" # => "one"
# Print all elements:
echo "${array[@]}" # => "one two three four five six"
# Print the number of elements:
echo "${#array[@]}" # => "6"
# Print the number of characters in third element
echo "${#array[2]}" # => "5"
# Print 2 elements starting from fourth:
echo "${array[@]:3:2}" # => "four five"
# Print all elements each of them on new line.
for item in "${array[@]}"; do
    echo "$item"
done

bash internal data manipulations array manipulation basic array operations

bash

This demonstrates removing a specified prefix from a variable's value using parameter expansion.


${FOO##prefix}

bash internal data manipulations string manipulation and expansions parameter expansion prefix removal

bash

This demonstrates replacing all occurrences of a substring within a variable using parameter expansion.


${FOO//from/to}

bash internal data manipulations string manipulation and expansions parameter expansion string substitution

Previous 1 2 3 4

...

15 Next

bash

This demonstrates directory navigation using cd - to toggle between the current and previous directories.


pwd # /home/user/foo
cd bar/
pwd # /home/user/foo/bar
cd -
pwd # /home/user/foo

bash internal file and stream operations directory operations directory navigation

bash

This demonstrates printing the current working directory using the pwd command.

pwd

bash internal file and stream operations directory navigation print working directory

bash

This demonstrates declaring a variable as an integer type and incrementing its value by 1 in Bash.


declare -i count  # Declare as type integer
count+=1          # Increment

bash internal data manipulations other variable features variable types (integer)

bash

This demonstrates how to unset (delete) a variable in Bash.


unset foo

bash internal data manipulations other variable features variable unset

bash

This demonstrates using the IFS variable to split a comma-separated string and iterate over its elements in a for loop.


IFS=','

string="apple,banana,cherry"
for fruit in $string; do
    echo "Fruit: $fruit"
done

bash internal data manipulations string manipulation and expansions IFS (Internal Field Separator)

bash

This demonstrates the use of an inline if-else statement to check if the current user is rehan and print yes or no accordingly.


[[ $USER = 'rehan' ]] && echo 'yes' || echo 'no'

bash internal flow control tests (conditions)inline if-else

bash

This demonstrates printing the current Bash process ID using the $BASHPID variable.


echo "Current Bash PID: $BASHPID"

bash internal data manipulations other variable features process ID

bash

This demonstrates accessing all command-line arguments in a Bash script.


echo "All arguments: $@"

bash internal data manipulations positional arguments positional argument

bash

This demonstrates the use of built-in Bash variables to access script information like return values, process ID, and arguments.


echo "Last program's return value: $?"
echo "Script's PID: $$"
echo "Number of arguments passed to script: $#"
echo "All arguments passed to script: $@"
echo "Script's arguments separated into different variables: $1 $2..."

bash internal data manipulations positional arguments built-in variables

bash

This demonstrates redirecting both standard output and standard error to a single log file in Bash.


python hello.py > "output-and-error.log" 2>&1
# redirect both output and errors to output-and-error.log
# &1 means file descriptor 1 (stdout), so 2>&1 redirects stderr (2) to the current
# destination of stdout (1), which has been redirected to output-and-error.log.

bash internal file and stream operations stream redirection and piping combined redirection

bash

This demonstrates printing the current user's username using the built-in $USER variable.


echo "Current user: $USER"

bash internal data manipulations environment variables built-in environment variables

bash

This demonstrates the use of an integer variable and a conditional while loop in Bash to decrement and print values.


declare -i counter
counter=10
while [ $counter -gt 2 ]; do
  echo The counter is $counter
  counter=counter-1
done

bash internal loops while loop conditional

bash

This demonstrates the use of a subshell to isolate directory changes, ensuring the main shell's working directory remains unchanged.


(cd somedir; echo "I'm now in $PWD")
pwd # still in first directory

bash internal process management subshell execution

bash


for i in {0..10..2}
  do
    echo "Index: $i"
  done

for filename in file1 file2 file3
  do
    echo "Content: " >> $filename
  done

for filename in *;
  do
    echo "Content: " >> $filename
  done

bash internal loops for loop numerical range iteration

bash

This demonstrates removing the longest matching suffix from a string using parameter expansion.


${FOO%%suffix}

bash internal data manipulations string manipulation and expansions parameter expansion suffix removal

bash

This demonstrates various methods of redirecting stdout and stderr in Bash, including appending, discarding, and combining streams.


python hello.py > output.txt            # stdout to (file)
python hello.py >> output.txt           # stdout to (file), append
python hello.py 2> error.log            # stderr to (file)
python hello.py 2>&1                    # stderr to stdout
python hello.py 2>/dev/null             # stderr to (null)
python hello.py >output.txt 2>&1        # stdout and stderr to (file), equivalent to &>
python hello.py &>/dev/null             # stdout and stderr to (null)
echo "$0: warning: too many users" >&2  # print diagnostic message to stderr

bash internal file and stream operations stream redirection and piping stdout redirection

bash

This demonstrates the use of a case statement to evaluate user input for weather conditions and print corresponding messages.


echo "What's the weather like tomorrow?"
read weather

case $weather in
  sunny | warm ) echo "Nice weather: " $weather
  ;;
  cloudy | cool ) echo "Not bad weather: " $weather
  ;;
  rainy | cold ) echo "Terrible weather: " $weather
  ;;
  * ) echo "Don't understand"
  ;;
esac

bash internal flow control tests (conditions)case statement

bash

This demonstrates basic array manipulation in Bash, including accessing elements, counting, slicing, and iterating.


array=(one two three four five six)
# Print the first element:
echo "${array[0]}" # => "one"
# Print all elements:
echo "${array[@]}" # => "one two three four five six"
# Print the number of elements:
echo "${#array[@]}" # => "6"
# Print the number of characters in third element
echo "${#array[2]}" # => "5"
# Print 2 elements starting from fourth:
echo "${array[@]:3:2}" # => "four five"
# Print all elements each of them on new line.
for item in "${array[@]}"; do
    echo "$item"
done

bash internal data manipulations array manipulation basic array operations

bash

This demonstrates removing a specified prefix from a variable's value using parameter expansion.


${FOO##prefix}

bash internal data manipulations string manipulation and expansions parameter expansion prefix removal

bash

This demonstrates replacing all occurrences of a substring within a variable using parameter expansion.


${FOO//from/to}

bash internal data manipulations string manipulation and expansions parameter expansion string substitution

Previous 1 2 3 4

...

15 Next