When passing arguments to scripts in Linux, there exists a fundamental system limit called ARG_MAX defined in limits.h. This defines the maximum combined length of command-line arguments and environment variables.

#include <stdio.h>
#include <limits.h>

int main() {
    printf("ARG_MAX: %ld\n", sysconf(_SC_ARG_MAX));
    return 0;
}

On modern Linux systems (kernel 2.6.23+), you'll typically find:

• Default value: 2MB (2097152 bytes)
• Minimum guaranteed value: 32KB (32768 bytes)
• Actual limit varies by system configuration

Several ways to check the limit:

# Using getconf
getconf ARG_MAX

# Checking kernel parameter
cat /proc/sys/kernel/args-max

# For per-process limit check
ulimit -s

When approaching the limit, consider these alternatives:

# 1. Use stdin redirection
echo "very_long_data_here" | myscript

# 2. Use temporary files
tmpfile=$(mktemp)
echo "very_long_data_here" > $tmpfile
myscript --input-file=$tmpfile
rm $tmpfile

# 3. Use environment variables (limited by ENV_MAX)
export LONG_VAR="very_long_data_here"
myscript

For systems requiring larger limits (e.g., big data processing):

# Temporary increase
sudo sysctl -w kernel.arg_max=4194304

# Permanent change (add to /etc/sysctl.conf)
kernel.arg_max = 4194304

• Always validate input length in scripts
• Consider argument chunking for very large data
• Document expected limits in your script's help
• Use proper error handling for boundary cases

When working with Linux command line arguments, there are actually several different limits to consider:

• ARG_MAX: Maximum total length of command line arguments
• MAX_ARG_STRLEN: Maximum length of a single argument
• MAX_ARG: Maximum number of arguments

You can check these values on your system using:

getconf ARG_MAX
getconf MAX_ARG_STRLEN

Or examine them directly:

cat /proc/sys/kernel/arg_max
xargs --show-limits

Here's a script to test argument length limits:

#!/bin/bash
# test_arg_length.sh

# Generate a long string
long_arg=$(printf '%*s' 100000 | tr ' ' 'A')

# Attempt to pass it
echo "Testing with argument length: ${#long_arg}"
./process_arg.sh "$long_arg"

When you hit these limits, consider these approaches:

# 1. Use environment variables
export LONG_VAR="your_long_string"
./script.sh

# 2. Use a file
echo "your_content" > tempfile
./script.sh @tempfile

# 3. Use xargs
printf '%s\n' "$long_var" | xargs -0 ./script.sh

Different systems may have different defaults:

• Linux: Typically 2MB total (ARG_MAX)
• MacOS: Around 256KB
• BSD Systems: Varies by version

To avoid hitting these limits:

1. Use configuration files for complex setups
2. Consider splitting very long arguments
3. Use environment variables when appropriate
4. Document your script's requirements